Technical Resources
With over 100 combined years of audio measurement experience, our team has created a wealth of technical papers, sequences, articles and other useful information to assist you with your audio test needs. Please browse the collection below, or filter by type of resource.
Microphone Acoustic Overload Point (AOP)
This sequence measures the acoustic overload point (AOP) of a microphone – the SPL required to produce 10% THD @ 1kHz from the microphone’s output.
A 1 kHz amplitude sweep from a calibrated source speaker is applied across a range from 120 dB SPL to 135 dB SPL.The recorded time waveform is then analyzed using the HarmonicTrak algorithm to produce a Fundamental and THD vs. Level curve. An intersection post processing function identifies where the THD curve intersects 10% and that level is is used in a limit step to produce a Pass/Fail AOP verdict.
RT60 Room Acoustics
The RT60 room acoustics sequence measures reverberation time and clarity of a room using multiple microphones to accurately characterize measurement environments. This is important for smart device testing as measurements of both speech recognition and audio output often need to be made in fully characterized rooms with known reverberation times and clarity. The method used in this sequence is fast, accurate, and made using fully calibrated signal paths. This sequence uses an omnidirectional speaker to play a Log Sweep from 250Hz – 15kHz and four microphones measure the impulse responses generated. These waveforms are analyzed using the Time Selective Response and room acoustics algorithms to calculate reverberation time (T20, T39, T60) and clarity (C7, C50 and C80) according to ISO 3382-1:2009.
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SoundCheck 19 New Features Video
In this short video, sales engineer Les Quindipan gives a brief overview and demonstration of the new features and functionality of SoundCheck 19, including the multichannel RTA, RT60 Room Acoustics module, AmpConnect 621 control, and more.
Measurement of Stereo Soundfield Parameters
The stereo soundfield sequence measures parameters such as Interaural level difference (ILD) and interaural cross-correlation (IACC) using a Head and Torso Simulator (HATS). The spectrum is measured at each ear and calculates interaural level differences (ILD), spectral balance, delay differences, and interaural cross-correlation (IACC). The measurements are made using different time windows, so that the direct, early, late or total parts are separated.
Several different signals are applied to the left and right inputs of the device under test (DUT), and the measurements are made with the HATS left and right ears. Up to 9 measurements in varying positions are made and saved. Results for each position are displayed, and on completion of the testing, means and standard deviations are shown.
TIA-5050 Test Sequence for Narrowband (NB) and Wideband (WB) Mobile Handset Phones
TIA 5050 is a US standard with measurement methods and requirements for the receive volume control performance of both narrowband (NB) and wideband (WB) mobile handset phones. The measurements include conversational gain, frequency response, and distortion. Measurements are made at both 2N and 8N handset application forces, with different requirements applied to each. Either Free Field (FF) or Diffuse Field (DF) can be chosen as the Listener Reference Point (LRP) for receive frequency response.
Display Tutorial
Our series of basic SoundCheck training instructional videos concludes with 7 short videos highlighting the different display options ranging from simply x-y graphs and tables to polar plots, and display customization, and of course how to use all these options in a sequence.
Part 1: Display Step Basics
Part 2: Display Configuration
Part 3: Graph Palettes
Part 4: X-Y and Waveform Graphs
Part 5: Tables, Text and Pictures
Part 6: Results
Part 7: Polar Plot
How to Measure Free Field Speaker Response without an Anechoic Chamber
Did you know
you can make free-field measurements without an anechoic chamber? In the March 2021 issue of VoiceCoil, Steve Temme explains his unique method for achieving this. The article explains how the ‘splice’ method results in a full range frequency response from a combination of near-field and windowed far-field measurement, and compares the results with anechoic chamber measurements and the manufacturer’s published response curve.
Anechoic Response of a Loudspeaker Without an Anechoic Chamber: Splice Sequence
This sequence measures the anechoic response of a loudspeaker in an ordinary room using both a near field and time-windowed far field measurement “spliced” together to cover the full bandwidth of the loudspeaker’s response from 20 Hz to 40 kHz. First, the microphone is placed very close to the low frequency driver (less than an inch from the woofer), and the near field frequency response measured using a 1/12th octave stepped sine). Next, the microphone is placed in the far field and the frequency response is measured using a continuous log sweep with the Time Selective Response analysis algorithm. An option is available for measuring a ported loudspeaker. The sequence displays both measurements on a graph, showing the overlap range where the measurements are equal. From this, the user selects the precise frequency at which to splice the two halves of the measurements together to obtain the full range free field response of the loudspeaker.
