Methodology Overview
Creating a sound impression using headphones involves simulating the spatial characteristics of sound,
which would typically be experienced in a real-world environment. The goal is to reproduce the acoustic
properties of a physical space, such as a room or concert hall, to provide the listener with a sense of
being surrounded by sound sources. This is commonly known as spatial audio or virtual surround sound.
Here are the key steps involved in creating a sound impression using headphones:
1. Room Impulse Response (IR): The Room Impulse Response (IR) represents the acoustic characteristics
of a physical space. It is a measurement of how sound propagates and reflects within a room or
environment. The IR captures the sound reflections, early reflections, and reverberation properties of
the room. It is typically obtained by capturing an audio signal in the room and then measuring the
response of the room to that signal.
2. Binaural Impulse Response (BRIR): The Binaural Impulse Response (BRIR) is a special type of IR that is
specific to binaural audio, which is audio recorded with two microphones to mimic human hearing.
BRIRs are used to model the way sound arrives at the ears of a listener when it comes from different
directions in a virtual environment. BRIRs are essential for achieving accurate spatial audio rendering
when using headphones.
3. RSAO Parameters: RSAO (Reverberant Spatial Audio Object) parameters are used to encode the
spatial and acoustic properties of the room into a format suitable for spatial audio rendering. These
parameters include information about the room volume, source-receiver distances, absorption
coefficients, and early reflections. The RSAO parameters are obtained through encoding techniques like
the RAOEncoder used in the provided code.
4. Convolution: Convolution is the process of combining the audio signal with the IR or BRIR.
Convolution takes the input audio and filters it through the IR or BRIR, effectively simulating the sound's
interaction with the room's acoustics. This process adds spatial information to the audio, making it
sound as if it is coming from different directions in a virtual space.
5. Diffuse Field Equalization (DFEQ): DFEQ is used to compensate for the frequency response of the
headphone and the acoustic properties of the listener's ears. It helps create a more accurate and
consistent perception of sound across different headphones and listeners.
By combining these steps, spatial audio rendering creates the impression of sound sources coming from
specific directions in a virtual environment. When the listener wears headphones, the audio signals
filtered through the BRIR and DFEQ produce an immersive and realistic sound experience, making it feel
as if the sound is coming from various directions around them.
In summary, the use of IRs, BRIRs, RSAO parameters, convolution, and DFEQ all play crucial roles in
creating a convincing sound impression using headphones. This technology is widely used in virtual
reality, gaming, music production, and other applications where a realistic and immersive audio
experience is desired.