APx511B Series Audio Analyzer

Ideal for production test of hearing aids

APx511B Series Hearing Instrument Audio Analyzer

The APx511B Series audio analyzer is designed specifically for the needs of hearing instrument manufacturers, providing the specific measurements and I/O required for hearing instrument production test, delivered with Audio Precision’s reputation for high performance and reliability.

APx511 supports a .NET library of functions that automate the tests described in IEC60118- 7 and ANSI S3.22. For the production environment, these functions can be called from any .NET capable language or LabVIEW to control the APx511’s output and measurement settings.



Code-Free Automation and a Complete API

APx500 Measurement Software is the most advanced audio measurement interface available. Complex procedures that include user prompts, limits, and calls to external applications can be created directly in the GUI, saving time and money while ensuring painless updates over time, as no development is required.

Create custom interfaces and application-to-application automation using the comprehensive APx API. Extensive documentation and examples are provided for Visual Basic.NET, C#, MATLAB, LabVIEW, and Python. Projects and automation can be shared with other APx units anywhere in the world.

Automated Routines for IEC60118-7 and ANSI S3.22

The APx511 supports a .NET library of functions that automate the tests described in IEC60118- 7 and ANSI S3.22. For the production environment, these functions can be called from any .NET capable language or LabVIEW to control the APx511’s output and measurement settings.

For troubleshooting or test setup, the APx511 can be controlled by the standard APx500 software providing a rich graphical user interface and access to automated reporting, real-time signal monitors, high resolution FFTs and controls for limits & other settings.

In addition to standard audio tests such as level, distortion, frequency response, and attack & release, the APx511 can measure battery current using its built-in battery simulator circuit.

Transfer Function

The transfer function measurement provides the complex frequency response function for a device, including the magnitude and phase (or real and imaginary components), using any broadband signal.

This feature, a powerful addition to APx software’s Sequence Mode, allows any APx analyzer to be used as a multichannel dynamic signal analyzer or as a so called dual-channel FFT analyzer. With transfer function and any broadband signal, including speech, music, or noise, APx users can now assess the complex frequency response, coherence, and impulse response of their device or system.

AP’s transfer function provides gapless and overlapped analysis of multiple acquisitions. It also includes a ground-breaking signal-based triggering that eliminates the need for a pilot tone in open-loop test applications, making it ideal for test of “smart” audio devices.

Built-in Support for Test Chamber Speaker, Telecoil & Microphone

The APx511 generator includes an in-line 4 watt loudspeaker amplifier (8 ohms) and a telecoil amplifier, allowing >110 dB SPL and up to 400 mA/m field strength from 100 Hz to 10 kHz in a test chamber such as the Interacoustics TBS25. On the input side, APx511 supplies 24 V DC of constant current through a single BNC for a pre-polarized measurement microphone.

Open-Loop Chirp

APx500 software enables open-loop measurements using the logarithmically-swept sine, or chirp, test signal. This signal provides multiple, high-resolution results in a brief period of time and APx users can employ the chirp in test scenarios where the signal may originate, or terminate, as a file on the device under test (DUT) or on a server connected to the DUT. This capability is especially helpful to those developing smart devices (e.g., smart speakers, smartphones).

Common Software Platform

APx audio analyzers use a common software platform, making tests and results easier to share. All settings for a test are saved in a single project file, making it easy to replicate test setups between R&D and production facilities anywhere in the world. Project files are compatible with both B Series and legacy APx instruments and each project is self-contained, so there’s never any worry about dependencies or broken links. Users can even embed waveform files and images within a project file.

For sharing measurement results with customers, contract manufacturers or management, APx automatically generates rich graphic reports, with highlighted pass / fail limits and options to export as PDF, HTML, Excel, CSV, RTF or MATLAB files.



The APx HA-1 2cc coupler (for In-the-Ear models) and HA-2 2cc coupler (for Behind-the-Ear models) meet IEC126 and are available for use with any ½-inch or 14 mm measurement microphone.


APx500 software options provide measurements and functionality beyond the core set of capabilities. A variety of options are offered, suited to different specific test applications and requirements.

For B Series APx analyzers, and legacy APx analyzers running version 5.0 software, software option licenses are electronically activated and are tied to a specific analyzer via serial number. For legacy APx analyzers running APx software version 4.6 or earlier, software option licenses are enabled by “iButtons” that mount on the rear of the instrument.

Perceptual Audio Test: POLQA (SW-POLQA-2)
Perceptual audio measurement returns a subjective assessment of speech quality using the next-generation POLQA algorithm for wide-band speech devices or devices with acoustic coupling. (Successor to PESQ with support for HD Voice, 3G, 4G/LTE and VoIP technologies)

Speech Intelligibility: ABC-MRT Measurement (SW-ABC-MRT)
The APx ABC-MRT plugin is a software option for APx500 audio measurement software that provides speech intelligibility measurement based upon the ABC-MRT speech processing algorithm developed by the Institute for Telecommunication Sciences (ITS) of the United States National Telecommunications and Information Administration (NTIA).

Speech Intelligibility: Speech Transmission Index (SW-STI)
SW-STI is a plug-in for conducting Speech Transmission Index (STI) measurements using the STIPA method.

Specifications & Requirements


  • Maximum output
    4 W RMS into 8 Ω (100 Hz 10 kHz BW)
  • THD+N
    -80 dB @ 2 W / 8 Ω (100 Hz 10 kHz BW)
  • Frequency Response
    ±0.1 dB (100 Hz 10 kHz)
  • Amplitude Accuracy
    ±0.03 dB (+15° C to +30° C)
  • Frequency Accuracy
    3 ppm


  • Maximum output
    100 mA RMS up to 20 Ω (100 Hz 10 kHz BW)
    (400 mA/m field strength in Interacoustics TBS25)
  • Total Harmonic Distortion
    -80 dB @ 100 mA into 1 Ω (100 Hz 10 kHz BW)
  • Frequency Response
    ±0.1 dB (100 Hz 10 kHz)
  • Frequency Accuracy
    3 ppm


  • Maximum Current
    30 mA
  • DC Output
    Range: 0 to 2 V; Resolution: 0.5 mV;
    Accuracy: ± (1% + 10 mV)
  • Output Impedance
    4.3 Ω
  • Current Measurement
    Range: 0 to 30 mA; Resolution: 10 µA;
    Accuracy: ± 5%


  • Connector type
    BNC (includes constant current power for a standard pre-polarized measurement microphone. CCP can be also disabled for use with an external microphone power supply)
  • Power
    24 V DC constant current
  • Maximum Input
    8.5 Vrms (equivalent to 151 dBSPL at mic sensitivity of 12.5 mV/PA)
  • Residual Noise (20 kHz BW)
    < 1.3 uV (equivalent to 20 dBSPL at mic sensitivity of 12.5 mV/PA)
  • Frequency Response
    ±0.03 dB (100 Hz 20 kHz)

APx511 B Series Full Specifications


  • Microsoft Windows 10 (64-bit) operating system.
  • USB 2.0 or USB 3.0. Two are required for optional switcher or DCX-127 use.
  • Intel i5 or better processor running at a clock speed of at least 2.5 GHz. AMD processors with similar specifications are also supported.
  • At least 8 GB RAM. 16 GB is highly recommended.
  • Internet connection or an USB Type A port (to access APx500 software for installation).
  • At least 1.5 GB of free hard disk space. An SSD for the operating system drive is recommended.
  • A color monitor and video card with at least SXGA (1280 X 1024) video graphics support. Video resolution of 1900 x 1080 or greater is recommended.
  • More detailed information is available on our AP Software and Windows Compatibility chart


  • System performance is sensitive to processor speed; faster processors will yield faster results.
  • APx500 is data intensive and it is recommended that other data-intensive applications not be run concurrently. This includes Audio Precision AP2700, APWIN or ATS.