Professional Audio & Video Blog

Perceptual audio analyse met APx 525

Perceptual audio analyse met APx 525

PERCEPTUAL AUDIO TESTING (PESQ) OPTION

APx500 v3.0 now supports a PESQ (Perceptual Evaluation of Speech Quality) option for use with APx audio analyzers. Obtain MOS results directly in APx projects,

PESQ is a widely used, enhanced perceptual measurement for voice quality in telecommunications. It was developed by OPTICOM GmbH and forms the basis of ITU-T Recommendation P.862. PESQ is specifically designed for testing voice quality on low bandwidth devices, like mobile phones and smartphones. MOS (Mean Opinion Score) results from PESQ can achieve a very high correlation with results obtainable using human subjects. 

When regular audio tests are not enough

Many voice communications devices, notably mobile phones and VoIP networks, employ limited bandwidth and/or bitrate, and use codecs that significantly alter sound. Despite these accommodations, people can usually understand one another quite well over these systems; this is because the compromises made are selected to allow adequate speech perception despite measurable shortcomings in distortion, frequency response, and other traditional audio measurements.

PESQ simulates the likely results of real human subjects with real speech samples, allowing designers of speech-delivery systems to ensure that real-world customers achieve high levels of product satisfaction.

PESQ methodology

In traditional perceptual measurements, a group of people is assembled and asked to judge the sound quality of various audio clips, typically on a scale from 1 to 5. When all the individual scores are tallied, the result is called the Mean Opinion Score (MOS).

Tests with real human subjects are expensive and time consuming, but these limitations can be overcome by using tools that incorporate algorithms based upon psychoacoustic modeling, such as PESQ. This automation allows for rapid iterations in development as well as efficient production line verification. Measurements obtained are classified as objective because they are unaffected by human temperament or test conditions, and the results are completely repeatable

Related Solutions

  • SoundWireSM Audio Testing with APx and LnK

    Testing semiconductor audio devices with a SoundWire interface using an Audio Precision APx audio analyzer is conceptually straightforward; the test strategy and implementation is no different than with any other IC device.

    The challenge is the connection to the SoundWire interface, and configuring the SoundWire device. We can with APx and LNK interface!

  • Audio Precision Adds STI (STIPA) Measurement Capability to APx500 Software

    Quantifying the Intelligibility of Speech

    Developed as a method for quantifying the intelligibility of speech with respect to a transmission medium—for example a room, an intercom system, a radio link—STI is an objective measure that provides a single rating between 0 and 1 that predicts the likelihood of syllables, words and sentences being comprehended within the intended medium. The rating is broken down into qualification bands ranging from “bad” (0 to 0.36), to “excellent” (0.75 to 1.0).

  • Lip-Sync The time alignment of the audio relative to the video

    I think you know the problems when audio and video are not in sync, what to do?

    We can give you the figure when you are out of sync to get it back easy.

    In both professional and consumer television and A/V systems, divergent audio and video signal paths and the delay inherent in digital processing provide many opportunities for the program sound and picture to fall out of synchronization

Supplier

  • Audio Precision

    Measurement solutions for all things audio.

    Audio measurement- and audio analysis instruments.

Related Blog messages

  • What is new in APx software 4-4

    The latest release of APx500 audio measurement software, version 4.4, is available for download at AP.com.

    The release includes minor feature improvements, including regulation enhancements and the option to maintain Bluetooth® connection even when Bluetooth is not selected as output or input.

    APx500 Measurement Software
    (Must be a registered user of AP.com
    and logged in to download)

  • PDM option for APx

    Pulse Density Modulation (PDM) is a one-bit, high rate data stream that conveys a signal by modulating the density of the pulses. A typical application for PDM is the Micro-Electrical-Mechanical System (MEMS) microphone found on smartphones.

    The APx PDM option provides direct connectivity for audio devices that have a PDM output (such as a MEMS microphone) or input (such as the decimator on a smartphone chip). In addition to all the standard audio measurements, APx provides variable DC voltage, variable sample rate, and a PSR (power supply rejection) measurement to test the device’s full operating parameters. No other analyzer combines direct PDM connectivity with APx’s best in class speed, ease-of-use, and performance.