ANSI/CEA 2010-B 2014 Sequence for Subwoofer Maximum SPL

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This sequence measures the maximum peak SPL of a subwoofer according to ANSI/CEA 12010-B 2014. In this test, 1/3 octave band limited tone bursts are presented to the subwoofer across a 3 octave range from 20 Hz to 160 Hz. At each frequency, the stimulus level is increased in +3 dB increments until the harmonic (and non-harmonic) distortion and noise (HD+N) exceeds the specified threshold. The level is then decreased by 3 dB and the test continues with level increments of +1 dB until the HD+N threshold is again exceeded. The peak SPL of the fundamental at the last passing test level is recorded and the sequence continues to the next frequency. Peak SPL values are weighted according to the power spectrum defined in the standard and the Average Weighted SPL and final Broadband Peak SPL calculated as specified.

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In-Car Audio Measurements

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This sequence tests the impulsive distortion, frequency response, and maximum sound pressure level of a vehicle infotainment system to the methods outlined in the Audio Engineering Society Technical Committee on Automotive Audio (TC-AA) in-vehicle measurements white paper. This white paper aims to define repeatable and defined car audio system measurements and in addition to the measurement methods, contains information on standardized test configuration, for example microphone and seat positioning. Please contact the TC-AA for more information on this project. This test sequence may, of course, be used with your own in-house physical configuration if adherence to the TC-AA guidelines is not essential.

This sequence includes one master sequence, three subsequences, plus a level check subsequence for calibration. The three individual subsequence tests have also been included in a separate folder so they may be run standalone. The standalone sequences each have their own Bluetooth connect and disconnect steps.

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Polar Plot (MDT-4000 Turntable) Sequence

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This sequence measures the polar response of a loudspeaker in both the vertical and horizontal dimensions. It is designed to work with the Portland Tool & Die MDT-4000 turntable, and has all the necessary commands to automatically rotate it via RS-232. The sequence uses a log sweep stimulus with the Time Selective Response algorithm so that the measurements can be run in a non-anechoic environment. Note that the time window needs to be adapted to the user’s measurement space.

The sequence plays the stimulus and measures at 10 degree increments from 0 to 180 degrees. This process is repeated with the speaker positioned horizontally. The two results are mirrored to display full 360 degree polar plots for each axis. A directivity index curve is also calculated for each axis and is displayed at the end of the test.

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Receive Loudness Rating with ITU Real Speech Test Sequence

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The purpose of this sequence is to measure the Receive Loudness Rating (RLR) following the ITU-T P.79 standard using a Head and Torso Simulator (HATS). First, real speech from the ITU-T P.501 standard is sent to the Device Under Test (DUT) speaker by an electrical interface. The HATS right ear captures the DUT‟s speaker response. SoundCheck calculates the frequency response and then RLR based on that recording.

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Send Loudness Rating with ITU Real Speech Test Sequence

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The purpose of this sequence is to measure the Send Loudness Rating (SLR) following the ITU-T P.79 standard. This sequence can be used with handsets, headsets, and conference call devices. First, real speech from the ITU-T P.501 standard is played out of a mouth simulator. The Device Under Test (DUT) microphone then captures the signal and transmits this back to SoundCheck. SoundCheck calculates the frequency response function in 1/3 octaves and calculates SLR based on that frequency response.

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Hearing Aid Frequency Response Test Sequence

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This sequence follows the ANSI S3.22-1996 standard method for testing the frequency response of a hearing aid. An equalized stepped sine sweep from 8 kHz – 200 Hz is played at a level of 60 dBSPL through the anechoic box speaker, and the output of the hearing aid is analyzed with the Heterodyne algorithm to produce a frequency response. Next, the HFA (High Frequency Average) is calculated by averaging the response values at three frequencies (1000, 1600, 2500 Hz). The HFA is then subtracted by 20 dB. Two post processing steps are used to find the upper and lower frequency points at which the response curve intersects this calculated value (HFA – 20 dB). These are the high and low frequency cutoff points.

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Hearing Aid OSPL 90 Test Sequence

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This sequence follows the ANSI S3.22-1996 standard method for measuring the OSPL curve, the HFA value, and the Max OSPL value for a hearing aid. An equalized stepped sine sweep from 8 kHz – 200 Hz is played at a level of 90 dBSPL through the anechoic box speaker, and a broadband response curve is analyzed through the hearing aid. Next, the HFA (High Frequency Average) is calculated by averaging the values at three frequencies (1000, 1600, 2500 Hz), and this value is checked with a limit step. The Max OSPL is calculated by finding the maximum point on the broadband response. A limit is also applied to this value.

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Release Time Hearing Aid Test Sequence

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This sequence follows the ANSI S3.22-1996 standard method for testing the release time of AGC (automatic gain control) hearing aids. A 2 kHz sine tone is played at 90 dBSPL for 1 second and then immediately drops to 55 dBSPL for 2 more seconds. A band limited time envelope (1.5-2.5 kHz) is created and then run through a post processing step, which calculates the release time. It does this by calculating the time it takes the device to stabilize within 4 dB of its steady level.

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Loose Particles Sequence

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This sequence demonstrates how to use SoundCheck to detect loose particle defects in loudspeakers. Loose particles typically reveal themselves as randomly spaced impulses, so they may not be detected when performing frequency based measurements such as THD, even though they can be clearly heard as undesirable artifacts. The loose particle algorithm, which is an available function in all analysis algorithms, analyzes a time waveform to detect these impulses. The user sets a customized threshold level for detection.

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Complete Test Sequence

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The purpose of this sequence is to perform a full suite of basic measurements for a loudspeaker. A 500 mV stepped sine sweep from 20 kHz to 50 Hz is played through the speaker and measured via two channels of the audio interface. A calibrated reference microphone is connected to one of the channels, and an impedance reference is connected to the other.

A HarmonicTrak™ analysis step analyzes the recorded waveform from the reference microphone, and outputs frequency response, THD, Rub & Buzz, and various harmonic curves. A second analysis step analyzes the waveform from the impedance reference and outputs a curve of impedance versus frequency. A post processing step is used to estimate the characteristics of the impedance curve and calculates the max impedance, resonance frequency, and the Q of the resonance peak.

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