Acoustics Terminology Quiz

Acoustics-Related Terms

• Absorption: The process of sound energy being lost when it hits a fibrous surface. This happens due to the acoustic friction created by the fibers. While the sound wave doesn't slow down, it loses energy, making the sound quieter.
• Absorption Coefficient: A value represented as a fraction that indicates the amount of incident sound energy absorbed by a surface.
• Attenuation: This refers to the reduction in sound level, typically quantified in decibels per meter for air conditioning applications.
• Audiology: This is the scientific study and practical application of amplifying or improving sound for individuals with hearing difficulties.
• Background Noise (Ambient Noise): The constant, surrounding noise in a space.
• Boominess: When the lower frequencies in a room, especially those in the range of the male voice, are excessively reverberant.
• Break-in Noise: Noise from surrounding areas transferring into a duct through its walls.
• Break-out Noise: Noise transferring from inside a duct through its walls into the surrounding space.
• Bright/Lively: This describes a sound environment with a lot of treble reflections, giving the sound a feel of brightness or liveliness. It can be common in spaces like tiled bathrooms or kitchens, but excessive brightness can feel harsh and irritating.
• Dark/Dead: This term describes a sound environment lacking reflections and reverberation. While providing good sound isolation, it can also feel lifeless and uneasy.
• Dead Room: A room with an unusually large amount of sound absorption, leading to very minimal reflections.
• Decay: The gradual reduction in sound level, typically referring to the diminishing of reverberation.
• Decay Rate (RT-60): This represents the time it takes in seconds for reverberation to decrease from very loud to almost inaudible, a total sound level difference of 60dB. It varies depending on the space—for instance, it might be 1 second in a living room, but 4 seconds in a gym.
• Decibel(dB): This is the unit of measurement for sound pressure level, sound intensity level, and sound power level, providing a way to quantify sound loudness.
• Diffraction: The change in the direction of sound propagation when it encounters a barrier, causing bending.
• Diffuse Sound (Field): A sound field where sound reaches the listener with equal intensity from all directions.
• Diffusion: The scattering of sound waves in various directions caused by reflections off non-flat surfaces. This helps to break down echoes and create a more balanced sound environment.
• Direct Sound: This is the initial sound that travels directly from the source to the listener without reflecting off any surfaces. This is the most immediate and clear sound.
• Early Reflections: Reflections that reach the listener within 1/20 of a second after the direct sound. They blend with the direct sound, influencing its tonal characteristics and perceived direction.
• Echo: A sound that is reflected with a noticeable time delay from the original sound, enough to be heard as a separate instance.
• Frequency (Hertz, Hz, cps): This refers to the number of sound repetitions per second, determining a sound's tone or pitch. It's measured in cycles per second (cps), also known as Hertz (Hz).
• Frequency of Vibration: The number of complete cycles of a vibrating object per second.
• Impact Noise: Noise generated by the collision of two objects.
• Infrasonic: Sounds that fall below the human audible range, below 20 Hz.
• Intelligibility: A measure of how well a sound message can be understood based on its clarity. It’s often assessed through recognition tests like "cat, bat, tat, rat...".
• Intensity: Represents the amount of sound power that falls on, passes through, or crosses a specific unit area.
• Intermittent Sound: A sound that is discontinuous or fluctuates in sound pressure level, sometimes falling below measurable levels.
• Isolation: The separation of sounds using a barrier to prevent transmission.
• Masking: When the perception of one sound is difficult because the presence of another louder sound raises its threshold of audibility.
• Noise (Background Noise): Unwanted, usually interfering sounds present in a listening space, often caused by air conditioning or conversations.
• Noise Floor: Represents the strength of the background noise in a space, measured in decibels. A higher noise floor can make it difficult to hear and understand spoken words.
• Noise Isolation Class (NIC): A single-number rating that quantifies noise reduction between two rooms.
• Noise Reduction (NR): The reduction in noise sound pressure level.
• Noise Reduction Coefficient (NRC): A single-number rating derived from measured sound absorption coefficients of a material, based on readings at 250, 500, 1000, and 2000 Hz.
• NRC Rating: Stands for Noise Reduction Coefficient, it is a rating assigned for the absorption capabilities of a surface. It represents the percentage of sound absorbed by the surface. For instance, a surface with a 30% NRC absorbs 30% of the sound hitting it, reflecting the remaining 70%.
• Octave: A range of sound frequencies where the upper frequency is twice the lower frequency. The octave sequence for the note "C" starts at 31 Hz and goes up to 16kHz, passing through 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1kHz, 2kHz, 4kHz, and 8kHz.
• Outdoor-Indoor Transmission Class (OITC): This rating, using a weighted single number, assesses the sound reduction effectiveness of a partition separating an indoor space from the exterior.
• Pitch: A listener's subjective perception of the frequency of a pure tone.
• Reflection Coefficient: A measure that quantifies the reflectivity of a surface regarding sound.
• Reflections: Sound waves that bounce off a surface, changing direction but maintaining the same angle of incidence and reflection.
• Resonance: When the frequency of a sound source matches the natural frequency of a room, resulting in a significant increase in the amplitude of vibrations, or a booming effect.
• Reverberant Sound Field: A field where sound repeatedly reflects off the boundaries of an enclosed space, creating a complex and sustained sound environment.
• Reverberation: The continued presence of sound in an enclosed space after the initial sound source has stopped. It's caused by the accumulation of multiple reflections, merging into a sustained, diffused sound.
• Reverberation Time (RT): This refers to the time taken for sound intensity to decay by one millionth of its initial level after the sound source is stopped.
• Sabin: A unit used to measure sound absorption.
• Scattering: The irregular diffraction of sound in multiple directions.
• Signal-to-Noise Ratio (S/N Ratio): This is the difference in sound level in decibels between the desired sound and the background noise level. A higher S/N ratio indicates a clearer signal with less interference.
• Sonic Color: The perceived shift in emphasis within the frequency spectrum of a complex sound. A neutral sonic color is considered natural, while a sound can be described as having a warm color (emphasized lower frequencies), cold color (emphasized higher frequencies), or nasal color (emphasized mid-range frequencies).
• Sound (Waves): Fluctuations in air pressure caused by moving objects or air streams, perceived as sound when an acoustic wave reaches the ear. These waves travel outwards in a spherical pattern.
• Structure-Borne Sound: Sound that is transmitted through a solid structure, like a wall or floor.
• Transmission Coefficient: The ratio of transmitted sound energy to the energy of the sound wave that initially hit the surface.

Test your knowledge on essential acoustics-related terms such as absorption, attenuation, and audiology. This quiz will help you understand how sound behaves in different environments and the scientific principles involved in sound management. Perfect for students and professionals in sound engineering and audiology fields.