Headphone, Earbud & Headset Testing

While there is a fundamental similarity between the test method for loudspeakers, and testing headphones or earbuds – drive an acoustic transducer, acquire the result with a measurement microphone and analyze it – the latter is complicated by their mode of use. Due to the close coupling of earphones to the ears, and the acoustic transmission paths involved, measuring and characterizing the audio quality of headphones, earbuds and headsets present unique challenges to both the design engineer in an R&D lab and the test engineer on a manufacturing line.

Within this section of AP.com are a variety of resources discussing these challenges, key electroacoustic measurements, references to relevant measurement standards, acoustic test fixtures required for measuring headphones, headphone acoustics and various practical aspects of headphone measurements.

For simplicity, the various resources here will often refer to “headphone test”, so it is worth noting that it is a shorthand reference to the measurement and characterization of the audio quality of headphones and earphones (earbuds) intended for listening to music and other full-band audio content. Likewise, these discussions are applicable to headsets, but only insofar as they are used as headphones.

More specifically, headphones are classified according to their shape and how they couple to the ear. Primary earphone classifications are:

• Circumaural earphones completely surround the pinna (outer ear) and rest on the surface of the head surrounding the pinna. They may touch the pinna, but do not significantly compress it.
• Supra-aural earphones rest on the pinna.
• Intra-concha earphones are small earphones intended to rest within the concha cavity of the ear (the hollow just outside the ear canal).
• Insert earphones are small earphones which are intended to partially or completely enter the ear canal.
• Supra-concha earphones are intended to rest upon the ridges of the concha cavity.

Earphones are further classified as acoustically open or closed. Open earphones (also called nominally unsealed) intentionally provide an acoustic path between the external environment and the ear canal. Closed (or nominally sealed) earphones are intended to prevent any acoustic coupling between the external environment and the ear canal.

With the various types of headphones in mind, it is worth noting the importance of fit when testing. The fit of an earphone to the head and/or pinna can have a dramatic effect on performance. As such, acoustic test fixtures (ATF) play an important part in headphones test and a variety of these fixtures, chosen by headphone characteristics and applications, are discussed in the resources below.

AppNote: Headphone Electroacoustic Measurements

Due to the close coupling of earphones to the ears and the acoustic transmission paths involved, headphone measurements are complicated.

Our 26-page application note discusses these challenges, headphones types, measurement standards, headphone acoustics, acoustic test fixtures required for measuring headphones, and the practical aspects of headphone measurements. Objective measurements are also discussed.

GRAS 45CA Headphone Test Fixture Data Sheet

Headphone testing is complicated. The acoustic transmission paths involved in the close coupling of headphones, earphones and insert earphones (earbuds) to the ears must be considered; further, for measurements in noisy environments or testing ANC (active noise canceling) headphones, isolation is important

Technote 107: Measuring the Sound Pressure Level of Portable Audio Player HeadphonesDescribes how to measure the sound pressure level developed by portable audio players and their associated headphones, according to British Standard / European Norm 50332. Also shown is how to use the APx Portable Audio Player / Portable Headphone Test Utility to facilitate making the necessary measurements with an APx500 analyzer.