The head-related transfer function measurement system is working with the impulse response measurement system "AEIRM" and the Microphone traverse system "MT series", to measure a numerous number of head-related transfer functions automatically in a short time.
Head-Related Transfer Function (HRTF) is defined as the transfer function from the point which is the center of the subject's ears without head to the opening of the subject's ear canal or the ear drum with head in a free field. In simple terms, HRTF describes how sound propagation is influenced by the shape of human head and ear.
HRTF is known as a fundamental data of auditory directional perception, and it can be used for various purposes from basic study to the surround audio system and realization of 3-D acoustics.
We are surrounded by various sounds in our daily life. Therefore, it is important to present the sound from various directions surrounding us to produce the 3-D effects without increasing the loudspeakers.
With our sound field reproduction system "OSS", you can hear the sound from various directions with two loudspeakers. For the realization of these functions it is important to understand the behavior of the HRTF as a basic data of human hearing perception.
There are two ways to measure HRTF, the first one is by using a dummy head microphone, second one is actual measurement with a human as the subject. The dummy head microphone with a pair of built-in microphones in both ears imitates an average human face and ear geometry. However, how we hear is different as all of us have different shapes of heads, ears, and shoulders. There are various kind of dummy head microphone with different shapes of heads and ears. Therefore, we have to keep in mind that it has an average shape of a human face and ears when we use for the purpose to achieve the virtual reality.
Moreover, HRTF depends on the direction. An automated measurement using the Microphone traverse system is effective to measure HRTF towards all directions.