hearing.audiometry

Pure-tone audiometry: the test room, the threshold rules and their uncertainty (ISO 8253-1:2010).

ISO 8253-1 sets out how a hearing threshold level is measured with earphones or a bone vibrator. Three parts of it are arithmetic, and this module carries them; the rest (preparing and instructing the subject, placing the transducers, masking, calibrating the audiometer) is procedure a tester follows.

The test room (Clause 11). The ambient noise must not mask the lowest test tone. Tables 2 and 4 give the maximum permissible ambient sound pressure levels $L_{S,\max }$ in one-third-octave bands from 31,5 Hz to 8 kHz, for air conduction with typical supra-aural earphones and for bone conduction, each for the lowest test frequency of the audiometry: 125 Hz, 250 Hz or, for air conduction, 500 Hz. They hold for hearing threshold levels down to 0 dB with at most +2 dB of threshold shift from the noise; the NOTEs allow 8 dB more for +5 dB, and 11.1 adds the lowest hearing threshold level to be measured when it is not 0 dB. An earphone that excludes more noise than the supra-aural one allows a louder room: 11.1 adds the difference between its attenuation and the supra-aural one of Table 3,

and Table 3 prints it for an insert (Etymotic ER-3A) and a circumaural (Sennheiser HDA 200) earphone. ambient_noise_limits returns the limits and check_audiometric_ambient_noise judges a measured spectrum against them, including the sound-field limits of ISO 8253-2:2009 Table 2 (phonometry.hearing.SOUND_FIELD_AMBIENT_LIMITS_DB).

The threshold (6.2.4, 6.3.5, 7.5). Each audiometric method ends in a rule that turns the subject’s responses into a hearing threshold level:

• the ascending method (6.2.3.2, 6.2.4.2) presents tones in 5 dB steps upwards until a response, drops 10 dB after each response, and stops when three responses fall at one level within at most five ascents (two out of three in the shortened version). The threshold is the lowest level at which responses occur in more than half of the ascents (ascending_method_threshold, which also replays a presentation sequence and gives the next level to present);
• the bracketing method (6.2.4.3) averages the lowest response levels of the ascents, and those of the descents, and rounds the mean of the two averages to the nearest 5 dB step (bracketing_method_threshold);
• automatic recording audiometry (6.3.5) averages the peaks and the valleys of the tracing, after dropping the first reversal and those of excursions of 3 dB or less, and rounds the mean of the two up to the next whole decibel (automatic_audiometry_threshold);
• sweep-frequency audiometry (7.5) averages the three peaks and the three valleys closest to a frequency, or runs that average along the tracing (sweep_audiometry_threshold).

Each also carries the text’s own reliability test: a span of more than 10 dB between the levels it averages.

The cautions (6.2.3.2, 8.4). Three more rules of the text judge the levels once they are found. Step 3 of 6.2.3.2 repeats the measurement at 1 kHz, and the first ear is done when the two agree to 5 dB or less (check_retest_agreement). A hearing level of 40 dB or more calls for caution because of cross-hearing (6.2.3.2), and a bone-conduction level at the average vibrotactile threshold of 8.4 may be felt rather than heard (VIBROTACTILE_HEARING_LEVELS_DB); audiogram_cautions flags both.

The uncertainty (Annex A). The hearing threshold level is modelled as the determined value plus seven zero-mean input quantities (Formula (A.1)), all uncorrelated with a sensitivity coefficient of 1, so the combined standard uncertainty is their root sum of squares (Formula (A.2)) and the expanded one twice that:

A.3 gives typical values for the repeatability, the audiometer, the transducer, the ambient noise and the masking; audiometric_uncertainty assembles them into an AudiometricUncertaintyBudget, and for air conduction below 4 kHz without masking it reproduces the example of Table A.2: $u$ = 4,9 dB and $U$ = 10 dB.

Clause, table and formula numbers refer to ISO 8253-1:2010(E).

Auto-generated from the source docstrings by scripts/generate_api_docs.py (make api-docs). Do not edit by hand.

Constant (mapping).

AIR_CONDUCTION_AMBIENT_LIMITS_DB = {125.0: array([56., 52., 47., 42., 38., 33., 28., 23., 20., 19., 18., 18., 18.,
       18., 20., 23., 25., 27., 30., 32., 34., 36., 35., 34., 33.]), 250.0: array([66., 62., 57., 52., 48., 43., 39., 30., 20., 19., 18., 18., 18.,
       18., 20., 23., 25., 27., 30., 32., 34., 36., 35., 34., 33.]), 500.0: array([78., 73., 68., 64., 59., 55., 51., 47., 42., 37., 33., 24., 18.,
       18., 20., 23., 25., 27., 30., 32., 34., 36., 35., 34., 33.])}

Constant (tuple).

AMBIENT_NOISE_BANDS_HZ = (31.5, 40.0, 50.0, 63.0, 80.0, 100.0, 125.0, 160.0, 200.0, 250.0, 315.0, 400.0, 500.0, 630.0, 800.0, 1000.0, 1250.0, 1600.0, 2000.0, 2500.0, 3150.0, 4000.0, 5000.0, 6300.0, 8000.0)

ambient_noise_limits(
    presentation: str = 'air',
    *,
    lowest_test_frequency_hz: float = 125.0,
    earphone: str = 'supra-aural',
    earphone_attenuation_db: ArrayLike | None = None,
    lowest_hearing_level_db: float = 0.0,
    allowed_threshold_shift_db: float = 2.0,
) -> np.ndarray

The maximum permissible ambient sound pressure levels of a test room.

For air conduction (ISO 8253-1 Table 2), bone conduction (Table 4) or sound field audiometry (ISO 8253-2 Table 2), in one-third-octave bands:

with the earphone term of 11.1 for air conduction (Table 3), the lowest hearing threshold level $L_{\mathrm{HT},\min }$ to be measured (11.1 and ISO 8253-2 Clause 6), and $\Delta$ = 8 dB when a threshold shift of +5 dB from the ambient noise is accepted instead of +2 dB (NOTE to Table 2, NOTE 1 to Table 4, footnote a to ISO 8253-2 Table 2). Where Table 3 prints no attenuation, the HDA 200 below 63 Hz, no allowance is made: the supra-aural earphone attenuates nothing there, so none is the conservative reading.

Parameters

Returns: The limits in dB re 20 µPa, one per band of AMBIENT_NOISE_BANDS_HZ for air and bone conduction and of phonometry.hearing.SOUND_FIELD_AMBIENT_BANDS_HZ for sound field.

Raises

AmbientNoiseCheck(
    presentation: str,
    frequencies: np.ndarray,
    levels_db: np.ndarray,
    lowest_test_frequency_hz: float,
    lowest_hearing_level_db: float,
    noise_floor_db: np.ndarray | None = None,
    earphone: str | None = None,
    earphone_attenuation_db: np.ndarray | None = None,
    allowed_threshold_shift_db: float = 2.0,
)

Whether a test room is quiet enough for the audiometry, band by band.

The fields hold what was measured and what the standard lets the tester choose: the presentation, the lowest test frequency, the lowest hearing level to be measured, the earphone and the threshold shift accepted. The limits themselves (limits_db) are read from the tables with those choices, so a check cannot be built against another table.

Attributes

A band the measurement leaves out is a band the room is not shown to meet, so passes needs every band of the table.

property

Whether the measurement gives every band the table limits.

Returns: True when no band of the table is missing.

property

The measured level less the limit per band, in dB.

Returns: Positive where the room is too loud.

property

Per band, whether the reading is within 6 dB of the noise floor.

11.1 asks the measuring chain for a noise floor at least 6 dB below the level it measures. A band that misses it reads high, so a band within its limit still is; one over its limit may be the floor’s.

Returns: One boolean per band, all False without a floor.

property

The maximum permissible level per band, in dB.

Returns: ambient_noise_limits of the presentation and the tester’s choices, at frequencies.

property

The lowest hearing threshold level this room lets be measured, in dB.

11.1 raises every limit by the lowest hearing threshold level to be measured, and ISO 8253-2 Clause 6 does the same for sound field audiometry, so the room allows the lowest level that brings every measured band under its raised limit. For sound field audiometry, ISO 8253-2 11.1 f) asks the report to state it when it is not 0 dB. ISO 8253-1 has no such reporting item: with earphones or a bone vibrator it is the level the rule of 11.1 implies.

Returns: lowest_hearing_level_db plus the largest exceedance.

property

Whether every band of the table was measured and is within its limit.

Returns: True when the room qualifies.

AmbientNoiseCheck.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Draw the measured spectrum against the limits, exceedances marked.

Parameters

Returns: The axes.

property

Every band the table sets a limit for, in hertz.

property

Per band, whether the measured level is at or below the limit.

Returns: One boolean per band.

ascending_method_threshold(
    ascent_levels_db: ArrayLike | None = None,
    *,
    presentation_levels_db: ArrayLike | None = None,
    responses: ArrayLike | None = None,
    shortened: bool = False,
    familiarization_level_db: float | None = None,
) -> AscendingThresholdResult

The hearing threshold level by the ascending method (6.2.3.2, 6.2.4.2).

The method presents tones of 1 s to 2 s. Step 1 starts 10 dB below the lowest level the subject responded to during familiarization and rises in 5 dB steps until a response; Step 2 drops 10 dB after each response until there is none, and ascends again in 5 dB steps. The series stops when three responses fall at one level within at most five ascents, or, in the shortened version, two within at most three. The hearing threshold level is then the lowest level at which responses occur in more than half of the ascents (6.2.4.2).

Give either the level at which each ascent ended in a response, or the whole presentation sequence with its responses. The sequence is replayed against the steps of 6.2.3.2, an ascent being a response reached from a tone that drew none, and the result says what to present next, which is the level a computer-controlled audiometer (6.4) can be given: call it with an empty sequence and the familiarization level for the first tone.

After five ascents without three responses at one level the series is exhausted, and 6.2.3.2 starts a new one 10 dB above the last response; that is a new call. 6.2.3.2 does not say what follows a shortened series that ends its three ascents without two responses at one level; the library’s choice is to continue it with the full method on the same presentations, a new call with shortened=False.

Parameters

Returns: AscendingThresholdResult.

Raises

AscendingThresholdResult(
    ascent_levels_db: np.ndarray,
    shortened: bool,
    next_level_db: float,
    presentation_levels_db: np.ndarray | None = None,
    responses: np.ndarray | None = None,
)

The hearing threshold level by the ascending method (6.2.4.2).

The threshold and the state of the series are read from the ascents by the stopping rule of 6.2.3.2, so they are not fields: a result cannot state a threshold its ascents do not reach.

Attributes

property

Whether the stopping rule is met.

Three responses at one level (two in the shortened version).

property

Whether the response levels span more than 10 dB (6.2.4.2).

The text says such a test should be considered of doubtful reliability, repeated, and noted on the audiogram.

Returns: True when the span exceeds 10 dB.

AscendingThresholdResult.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Draw the presentations, heard and not heard, and the threshold.

Parameters

Returns: The axes.

property

How many ascents ended at the threshold level.

Returns: The count, 0 when no threshold is determined.

property

Whether the series used up its ascents without a threshold.

Five ascents, or three shortened. The full method then starts a new series 10 dB above the last response.

property

The spread of the ascents’ response levels, in dB.

Returns: The largest less the smallest, 0 for fewer than two ascents.

property

The hearing threshold level, in dB.

The lowest level at which responses occur in more than half of the ascents, once the stopping rule of 6.2.3.2 is met; NaN until then.

audiogram_cautions(
    frequencies: ArrayLike,
    *,
    air_conduction_db: ArrayLike | None = None,
    bone_conduction_db: ArrayLike | None = None,
    vibrator_placement: str = 'mastoid',
) -> AudiogramCautions

Flag the levels of an audiogram that call for caution (6.2.3.2, 8.4).

Two rules of ISO 8253-1 judge a hearing threshold level by its size:

• cross-hearing (6.2.3.2): an air-conduction hearing level of 40 dB or more, in either ear at any frequency, is to be interpreted with caution, because the tone may reach the other ear; contralateral masking can then be necessary;
• vibrotactile sensation (8.4): with the bone vibrator on the mastoid, the vibrotactile threshold lies on average at a hearing level of about 40 dB at 250 Hz, 60 dB at 500 Hz and 70 dB at 1 kHz, about 10 dB lower for an audiometer calibrated for forehead placement, and a bone-conduction response at such a level may be felt rather than heard.

Give the levels of one ear; the caution of 6.2.3.2 holds for the results when either ear reaches 40 dB. Bone conduction gets no cross-hearing flag, because 40 dB is not its limit: 8.1 asks for the non-test ear to be masked at every level for a precise monaural result. 8.4 gives no vibrotactile level at other frequencies, where nothing is flagged, and its levels are averages about which individuals vary widely.

Parameters

Returns: AudiogramCautions.

Raises

AudiogramCautions(
    frequencies: np.ndarray,
    air_conduction_db: np.ndarray | None,
    bone_conduction_db: np.ndarray | None,
    vibrator_placement: str,
)

The levels of an audiogram that call for caution (6.2.3.2, 8.4).

Attributes

property

Whether any level is flagged by either rule.

Returns: True when some level calls for caution.

property

Per frequency, whether the air-conduction level is 40 dB or more.

6.2.3.2 asks for such results to be interpreted with caution because of cross-hearing: the tone may be heard by the other ear, and contralateral masking can be necessary.

Returns: One boolean per frequency, all False without air conduction levels.

AudiogramCautions.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Draw the audiogram with the caution levels and the levels flagged.

Parameters

Returns: The axes.

property

Per frequency, whether the bone-conduction level reaches 8.4’s level.

At or above the average vibrotactile threshold the subject may feel the vibrator rather than hear the tone, and 8.4 says care shall be taken that such a sensation is not taken for hearing.

Returns: One boolean per frequency, False where 8.4 gives no level or without bone conduction levels.

property

The average vibrotactile threshold of 8.4 at each frequency, in dB.

Returns: One level per frequency, 10 dB lower for forehead placement, NaN where 8.4 gives none.

audiometric_uncertainty(
    frequency: float,
    *,
    conduction: str = 'air',
    masked: bool = False,
    level_step_db: float = 5.0,
    environment_db: float = 2.0,
    tester_db: float = 0.0,
    subject_db: float = 0.0,
    special_db: float = 0.0,
) -> AudiometricUncertaintyBudget

The typical uncertainty budget of a hearing threshold level (A.3).

Fills Table A.1 with the values A.3 gives, which differ up to and above 4 kHz:

• $u_1$ (A.3.2): 2,5 dB and 4 dB for air conduction, 3 dB and 5 dB for bone conduction;

• $u_2$ (A.3.3): the audiometer’s maximum output deviation $a$ of IEC 60645-1 (±3 dB and ±5 dB for air, ±4 dB and ±5 dB for bone), rectangular, with the attenuator step $s$ rounding the level, also rectangular:

  $$u_2=\sqrt{{\left(\frac{a}{\sqrt{3}}\right)}^2+{\left(\frac{s}{2\sqrt{3}}\right)}^2}$$

  which for air conduction up to 4 kHz and 5 dB steps is 2,3 dB;

• $u_3$ (A.3.4): $\sqrt{1,5^2+2,5^2}$ = 2,9 dB up to 4 kHz and $\sqrt{2,5^2+3^2}$ = 3,9 dB above;

• $u_4$ (A.3.5): 2 dB when the ambient noise meets Clause 11 and the subject’s threshold is near 0 dB. It may be negligible for thresholds well above 0 dB and is considerably larger in a room that exceeds the limits; give it with environment_db;

• $u_5$ (A.3.6): 2 dB when masking noise is applied;

• $u_6$ to $u_8$ (A.3.7 to A.3.9): zero in usual situations, where the repeatability already covers them; give them when an exceptional situation calls for them.

For air conduction below 4 kHz without masking this is the example of Table A.2: $u$ = 4,9 dB and $U$ = 10 dB.

Parameters

Returns: AudiometricUncertaintyBudget.

Raises

AudiometricUncertaintyBudget(
    repeatability_db: float,
    equipment_db: float,
    transducer_db: float,
    environment_db: float,
    masking_db: float = 0.0,
    tester_db: float = 0.0,
    subject_db: float = 0.0,
    special_db: float = 0.0,
)

The uncertainty budget of a hearing threshold level (Annex A).

The eight standard uncertainties of Table A.1, each with a sensitivity coefficient of 1 and uncorrelated with the others (A.2), so the combined standard uncertainty is their root sum of squares (Formula (A.2)) and the expanded one is $U=ku$ with $k$ = 2 (A.5).

Attributes

property

$u=\sqrt{\sum u_i^2}$ (Formula (A.2)), in dB.

Returns: The combined standard uncertainty, unrounded.

property

The eight standard uncertainties in the order of Table A.1, in dB.

Returns: $u_1$ to $u_8$.

property

$U=2u$ for a coverage probability of 95 % (A.5), in dB.

Returns: The expanded uncertainty, unrounded; A.6 reports it rounded to the nearest full decibel.

property

The eight input quantities of Table A.1, in its order.

Returns: Their symbols.

AudiometricUncertaintyBudget.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Draw the eight contributions as bars, with the combined value.

Parameters

Returns: The axes.

automatic_audiometry_threshold(
    reversal_levels_db: ArrayLike,
) -> AutomaticThresholdResult

The hearing threshold level from an automatic recording (6.3.5).

The subject holds the level down while the tone is heard and lets it rise when it is not, so the tracing zigzags about the threshold. At one frequency, 6.3.5:

• a) ignores the first reversal after the change of frequency and every reversal of an excursion of 3 dB or less (both reversals that bound it);
• b) averages the remaining peaks, and averages the remaining valleys;
• c) takes the mean of the two averages, rounded up to the nearest whole number of decibels, as the hearing threshold level.

The recording is of doubtful reliability, and should be repeated, when the peaks or the valleys deviate by more than 10 dB from each other or fewer than six reversals remain after a). NOTE 2 to 6.3.5 puts automatic thresholds 3 dB lower on average than manual ones with 5 dB steps; that is a property of the method, and nothing here corrects for it.

Parameters

Returns: AutomaticThresholdResult.

Raises

AutomaticThresholdResult(
    reversal_levels_db: np.ndarray,
    mean_db: float,
    threshold_db: float,
)

The hearing threshold level from an automatic recording (6.3.5).

Attributes

Which reversals are peaks (is_peak) and which 6.3.5 a) keeps (retained) are read from the levels, so they are not fields.

property

Whether the recording should be repeated (6.3.5).

Returns: True when the peaks or the valleys deviate by more than 10 dB from each other, or fewer than six reversals remain.

property

Whether each reversal is a peak, a local maximum of the level.

The others are valleys. Read from the direction the trace turns at each reversal.

Returns: One boolean per reversal.

property

The retained peaks, in dB.

Returns: Their levels, in order.

AutomaticThresholdResult.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Draw the tracing through its reversals, the ignored ones faded.

Parameters

Returns: The axes.

property

Whether each reversal is kept after 6.3.5 a).

The first is ignored, and so are both ends of every excursion of 3 dB or less.

Returns: One boolean per reversal.

property

The retained valleys, in dB.

Returns: Their levels, in order.

Constant (mapping).

BONE_CONDUCTION_AMBIENT_LIMITS_DB = {125.0: array([55., 47., 41., 35., 30., 25., 20., 17., 15., 13., 11.,  9.,  8.,
        8.,  7.,  7.,  7.,  8.,  8.,  6.,  4.,  2.,  4.,  9., 15.]), 250.0: array([63., 56., 49., 44., 39., 35., 28., 21., 15., 13., 11.,  9.,  8.,
        8.,  7.,  7.,  7.,  8.,  8.,  6.,  4.,  2.,  4.,  9., 15.])}

bracketing_method_threshold(
    ascent_levels_db: ArrayLike,
    descent_levels_db: ArrayLike,
) -> BracketingThresholdResult

The hearing threshold level by the bracketing method (6.2.4.3).

The bracketing method ascends in 5 dB steps to a response, rises 5 dB and descends in 5 dB steps until there is none, three ascents and three descents in all, or two of each when their four lowest response levels are within 5 dB of each other (6.2.3.2). The threshold averages the lowest response levels of the ascents, averages those of the descents, and rounds the mean of the two averages to the nearest 5 dB step:

A mean halfway between two steps goes to the higher step, the rounding the library applies wherever a standard says “nearest” without a rule for the tie.

Parameters

Returns: BracketingThresholdResult, which also says whether the series is complete and whether 6.2.4.3 advises a repeat.

Raises

BracketingThresholdResult(
    ascent_levels_db: np.ndarray,
    descent_levels_db: np.ndarray,
    mean_db: float,
    threshold_db: float,
)

The hearing threshold level by the bracketing method (6.2.4.3).

Attributes

property

The average of the ascents’ lowest response levels, in dB.

Returns: The mean.

property

Whether the series is long enough (6.2.3.2 Step 2).

Returns: True for three ascents and three descents, or for two of each whose four levels differ by no more than 5 dB (the shortened version).

property

The average of the descents’ lowest response levels, in dB.

Returns: The mean.

BracketingThresholdResult.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Draw the ascents’ and descents’ levels, their means and the threshold.

Parameters

Returns: The axes.

property

Whether the ascents or the descents spread over more than 10 dB.

6.2.4.3 says the test should then be repeated.

Returns: True when either set of levels spans more than 10 dB.

check_audiometric_ambient_noise(
    levels_db: ArrayLike,
    *,
    presentation: str = 'air',
    lowest_test_frequency_hz: float = 125.0,
    earphone: str = 'supra-aural',
    earphone_attenuation_db: ArrayLike | None = None,
    lowest_hearing_level_db: float = 0.0,
    allowed_threshold_shift_db: float = 2.0,
    frequencies: ArrayLike | None = None,
    noise_floor_db: ArrayLike | None = None,
) -> AmbientNoiseCheck

Is the test room quiet enough for the audiometry? (ISO 8253-1 Clause 11).

Compares the ambient sound pressure level measured at the position of the subject’s head, with the subject absent and the room as it is during testing (ventilation running if it runs then), with the limits of ambient_noise_limits: ISO 8253-1 Table 2 for air conduction, Table 4 for bone conduction, or ISO 8253-2 Table 2 for sound field audiometry (its Clause 6).

With presentation="sound field" and narrow-band noise as the test signal, footnote b to ISO 8253-2 Table 2 says the limits should be lower than the table’s. It prints no figure for how much, so the check applies the table as printed, and a room that passes it may still be too loud for a narrow-band noise signal.

Parameters

Returns: AmbientNoiseCheck.

Raises

check_retest_agreement(
    first_db: float,
    repeat_db: float,
    *,
    frequency_hz: float = 1000.0,
) -> RetestAgreementCheck

Does the repeat measurement confirm the first? (6.2.3.2 Step 3).

Once every frequency of the first ear is tested, Step 3 repeats the measurement at 1 kHz. If the repeat agrees with the first measurement to 5 dB or less, the test proceeds to the other ear; if it shows an improvement or a worsening of 10 dB or more, the further frequencies are retested in the same order until agreement to 5 dB or less is obtained. ISO 8253-2 8.1 asks for the same repeat at 1 kHz in sound field audiometry.

The text is written for the 5 dB steps of a manual audiometer, where a difference is either 5 dB or less or 10 dB or more. A finer control can give a difference in between; it is not agreement to 5 dB or less, so it does not pass, and the text names no action for it, so RetestAgreementCheck.retest_further_frequencies is False too.

Parameters

Returns: RetestAgreementCheck.

Raises

Constant (mapping).

EARPHONE_ATTENUATION_DB = {'supra-aural': array([ 0.,  0.,  0.,  1.,  1.,  2.,  3.,  4.,  5.,  5.,  5.,  6.,  7.,
        9., 11., 15., 18., 21., 26., 28., 31., 32., 29., 26., 24.]), 'ER-3A': array([33., 33., 33., 33., 33., 33., 33., 34., 35., 36., 37., 37., 38.,
       37., 37., 37., 35., 34., 33., 35., 37., 40., 41., 42., 43.]), 'HDA 200': array([nan, nan, nan, 17., 16., 15., 15., 15., 16., 16., 18., 20., 23.,
       25., 27., 29., 30., 31., 32., 37., 41., 46., 45., 45., 44.])}

RetestAgreementCheck(first_db: float, repeat_db: float, frequency_hz: float)

Whether a repeat measurement confirms the first one (6.2.3.2 Step 3).

Attributes

property

The repeat less the first measurement, in dB.

Returns: Positive for a worsening, negative for an improvement.

property

Whether the two agree to 5 dB or less, and the test moves on.

Returns: True when the difference is at most 5 dB either way.

RetestAgreementCheck.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Draw the two measurements and the 5 dB either side of the first.

Parameters

Returns: The axes.

property

Whether Step 3 sends the test back to the further frequencies.

Returns: True for an improvement or a worsening of 10 dB or more.

sweep_audiometry_threshold(
    reversal_frequencies: ArrayLike,
    reversal_levels_db: ArrayLike,
    *,
    frequencies: ArrayLike | None = None,
) -> SweepThresholdResult

Hearing threshold levels from a sweep-frequency tracing (7.5).

The frequency sweeps continuously, normally at 0,5 to 2 octaves per minute, while the subject tracks the threshold as in automatic audiometry. At a specified frequency, 7.5 averages the three peaks and the three valleys of the tracing closest to it and takes the mean of the two averages, rounded to the nearest whole decibel, as the hearing threshold level there. Closest is measured on the logarithmic frequency axis the sweep runs on, and a mean halfway between two decibels goes up.

As a semicontinuous function of frequency, 7.5 runs the average along the tracing: each run of three consecutive pairs of peaks and valleys, six consecutive reversals, gives the arithmetic mean of its six levels at the geometric mean of its six frequencies,

and the run advances one reversal at a time.

Parameters

Returns: SweepThresholdResult.

Raises

SweepThresholdResult(
    reversal_frequencies: np.ndarray,
    reversal_levels_db: np.ndarray,
    frequencies: np.ndarray,
    mean_db: np.ndarray,
    threshold_db: np.ndarray,
    spread_db: np.ndarray,
    running_frequencies: np.ndarray,
    running_threshold_db: np.ndarray,
)

Hearing threshold levels from a sweep-frequency tracing (7.5).

Attributes

Which reversals are peaks (is_peak) is read from the levels, so it is not a field.

property

Whether each reversal is a peak, the others being valleys.

Read from the direction the trace turns at each reversal.

Returns: One boolean per reversal.

property

Per frequency, whether its peaks or valleys spread over 10 dB.

7.5 NOTE 1 calls such a determination less reliable.

Returns: One boolean per frequency.

SweepThresholdResult.plot(
    ax: Axes | None = None,
    *,
    language: str = 'en',
    **kwargs: Any,
) -> Axes

Draw the tracing, its running threshold and the thresholds found.

Parameters

Returns: The axes.

Constant (mapping).

VIBROTACTILE_HEARING_LEVELS_DB = {250.0: 40.0, 500.0: 60.0, 1000.0: 70.0}