Comparison of Wired and Wireless (Bluetooth) Speaker Response

bluetooth_speaker_responseThis test sequence performs frequency response and distortion measurements of a Bluetooth speaker using both a wireless Bluetooth and wired stimuli, and compares the results. This sequence is configured for use with a Portland Tool & Die BTC-4148 or BQC-4148 Bluetooth interface.

Initially, the sequence prompts the operator to turn on the Bluetooth device under test and set it to pairing mode. BTC message steps will connect the Bluetooth device (operator selects the device from a list of detected Bluetooth devices) and connects Bluetooth audio. A 1 kHz test tone is transmitted, and if detected, the test sequence proceeds. A stepped sine sweep from 20 kHz to 100 Hz is played wirelessly to the Bluetooth speaker and measured via a calibrated reference mic.

Two post-processing steps convert the sampling rate and alignment of the response, then an analysis step calculates the frequency response and THD. The Bluetooth is disconnected, and the Bluetooth frequency response and THD curves are displayed on graphs. The operator is then prompted to connect the wired analog input into the Bluetooth speaker, and the same measurements are performed using the analog connection. Analog frequency response and THD curves are temporarily displayed on graphs, followed by graphs containing both Bluetooth and analog curves for comparison.

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Linear Motor Test Sequence

linear_motor_test_seq_final_screenshotLinear motors (also known as linear vibrators or linear resonant actuators) have become increasingly popular in handheld devices such as phones and tablets for providing haptic feedback to the device’s user. The performance characteristics of these devices can now be tested using your SoundCheck system – the same software you are familiar with from your audio tests! The main difference between linear motor testing and audio testing is that an accelerometer (rather than a microphone) is used to measure the performance of the device under test.

A linear motor is designed to have a strong resonant frequency across a narrow frequency bandwidth; the motor is then operated at its resonant frequency to produce maximum output (vibration) while having minimal power demands on the portable device. The strength of the vibration is controlled by adjusting the magnitude of the AC signal input to the motor. In this sequence, first a sine sweep is applied to the device to calculate the resonant frequency, impedance and related values, and then a single tone at resonance is applied to measure characteristics such as rise and fall time.

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IEC-60268-7 Headphone Sequences

seq_IEC-60268-7_distortion_impedance_no borderIEC-60268-7: Sound System Equipment – Part 7: Headphones and Earphones is an international standard intended to characterize the performance of headphones and earphones. The standard itself is a lengthy document, 9 Sections and 3 Annexes covering 46 printed pages. These SoundCheck sequences focus on the electro-acoustic tests which are detailed in Section 8 “Characteristics to be specified and their method of measurement”.

Five separate sequences are provided, each designed to measure specific characteristics. This approach provides the user with the flexibility to measure all or some of the characteristics of their headphone.

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Triggered Record Using WAV File (Version 16.0 and earlier)

triggered_record_screenshotThis sequence allows you to test devices without an analog input such as tablets, cellphones and MP3 players. A stimulus WAV file is created in SoundCheck, and copied to the device under test, where it is played and the response recorded in SoundCheck as if the stimulus were played directly from SoundCheck. The stimulus WAV file to be used on the device under test (DUT) may be customized in the stimulus step.

Note that this sequence uses the level-based trigger available in SoundCheck 16.0 and earlier. If you are using version 16.1 or later, please see the frequency-trigger based sequence which takes advantage of new functionality to offer more robust triggering.

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EN 50332-1 – Max. SPL of Portable Audio Devices

EN-50332_1 screenshotThis sequence follows the test standard detailed in EN50332-1 (2013) for measuring the maximum sound pressure for portable music players and the earphones/headphones they are bundled with. The test involves loading a weighted pink noise stimulus file (as specified by IEC 268) onto the portable device and playing it through the earphones at the player’s maximum volume.

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AGC Hearing Aid – Reference Gain & EIN Test Sequence

This sequence performs two of the measurements from the ANSI hearing aid test standard S3.22-1996.  The first part, in accordance with section 6.7 of the standard, helps the user set the reference test gain for the hearing aid, which is used for multiple measurements in the standard.  The second part, from section 6.12, tests the equivalent input noise (EIN) of the device.

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ANSI S3.22 and IEC 60318-7 Hearing Aid Test Sequences

The Hearing Aid Standard suite of sequences contains all the major tests from ANSI S3.22 and IEC 60318-7, as well as some of the additional ‘Annex C’ sequences from the 2003 ANSI standard. Each test, as outlined in the standards, is contained in a single test sequence.  These sequences can each be run independently. There are also several full test sequences, which call up the required individual tests to run a complete standard test suite.

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Hearing Aid Compatibility to TIA 1083 and FCC Part 68.316

These two test sequences are designed to test the hearing aid compatibility of a telephone according to the TIA 1083 and FCC Part 68.316 standards. These sequences, which rely on the user having radial and axial HAC probes, play the appropriate test signals, measure the response and compare them to the limits in the standard. These pre-written sequences enable the user to immediately test to the relevant standards, and can be fully modified to meet any custom testing needs if desired.

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