One of the most important things that need to be taken into consideration when dealing with headphones measurement is using the right head microphone for the process. One of the standards used by different sound engineers is the Head Acoustics Artificial Head Measurement System in performing measurements in strict compliance with the standards implemented in the industry. This system has been designed to incorporate the very same characteristic for acoustic absorption as with human bone and skin.
Towards the bottom, there is a calibrated microphone. The moment a pair of headphones is placed on its head, the acoustic coupling on the microphones is pretty similar as with that on an actual human. The produced acoustic response on each head is then measured before the headphones leave the factory, making sure that calibration curves are also sent through with each of the heads.
Microphone Measurement Analysis
During the procedure, test signals are being generated, with the microphone returning signals that are analyzed using an Audio Precision System audio analyzer. With this, the headphones are being driven using a headphone amplifier.
Measurements are being completed at a volume of 90dB SPL @1kHz. A 90dB sound pressure level is the right gauge as it is just a little louder compared to a standard volume for listening. As such, the headphones need to reproduce well at this setup.
Here are the steps to headphones measurement:
- Place the headphone on the measuring device
- Close the chamber door
- Press the go button controlling the audio precision
- Audio Precision processes the scrip for measurement, performing the tests sequentially
- Data is save in a particular folder
- Data is uploaded on the site for display
Measurement Single-Point Specifications
Along with the procedures involved in headphones measurement, there are single point specifications involved. These specifications are presented readily on the product pages. They include factors such as isolation, impedance, total harmonic distortion, as well as other data points. These specifications are often provided by the manufacturers of the headphones.
The Importance of Headphones Measurement
Is measuring the capability of headphones really important? Well, yes if you are using headphones for reasons more than just casual listening of music. At this point, it is very important to understand that analyzing headphones measurement is not similar to analyzing speaker measurement.
With actual headphones, the standards for measurements existing are considered flawed and out of date. As such, different music technicians were moved to use certain techniques and methods in order to come up with accurate data. The equipment may be standardized accordingly, but because of the high cost involved in using headphone measurement gear, there are some manufacturers and reviewers who use improvised systems, such as a microphone flush mounted on top of a plate, rather than an actual system.
Vibration and Sound
There are also other ways to process the frequency response measurements of headphones. This works in attempt to making them correlate better with the actual ways in which human hear the sounds. The methods involved usually take into consideration the acoustical effects on the pinna, ear canal, as well as the head.
The measurements can be calibrated for drum reference point (DRP), referring the response at the eardrum, the ear entrance point (EEP), referring to the response found at the ear canal entrance, as well as the ear reference point (ERP), referring to the response at a particular point in space that is defined roughly by the intersection of the ear canal axis and the palm when the palm is pressed against the ear.
Some music technicians who perform headphones measurement use a diffuse-field compensation curve, with the purpose of countering the equalization that is often used on many headphones. Typically, these headphones come with a response peak of around +1dB on 3kHz. Therefore, by processing measurements with reverse compensation, such level will now appear as flat, which means, by theory, that it is the same way in which your ear actually perceives the sound.
Is the Interpretation Important?
Some claim that headphones measurements are valueless when it comes to judging the actual capabilities of headphones, and even in judging even other types of audio devices, tools and equipment. However, this is a common mistake that leads to choosing a low quality, and low performing headphone. It is very important to have at least a significant experience when it comes to evaluating different audio measurements, such as headphones. With such consideration in mind, if you are planning to buy a headphone, it would be best to look into the headphone measurement conducted on the unit you are purchasing in order to identify whether it is a good option for you.