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Mic Distance Delay Calculator

Calculate acoustic delay and sample offsets between microphones based on physical distance and air temperature. Visualize phase cancellations and comb filtering.

meters
°C
Speed of Sound
343.4 m/s (1,126.6 ft/s)
Delay Time
2.91 ms
Samples Offset (48k)
140 samples

Acoustic Comb Filtering spectrum

Phase cancellation notches caused by mixing delayed signals. Hover on graph to audit frequencies.

Primary Phase Cancellations (Nulls)

Frequencies that will completely cancel out when summed to mono:

171.7 Hz · 515.1 Hz · 858.5 Hz
Constructive Additions (Peaks)

Frequencies that double in volume (+6dB boost) when summed:

343.4 Hz · 686.8 Hz · 1030.2 Hz

What is the Mic Distance Delay Calculator?

The Mic Distance Delay Calculator is a specialized utility for live mixing engineers, broadcasters, and sound designers. It computes the precise acoustic travel time (delay) in milliseconds and sample offsets between two microphones based on their physical distance and air temperature.

Sound waves travel relatively slowly through the air compared to electrical signals. When the same acoustic source (like a drum kit, acoustic guitar, or podcast host) is picked up by two microphones placed at different distances, the sound arrives at the further microphone slightly later. When mixed together, this delay causes destructive phase interference, known as comb filtering.

By calculating the exact offset, you can apply digital delay to align the microphones in the time domain, eliminating cancellations and delivering a clear, punchy sound.

Comb Filtering and Phase Cancellations Explained

Comb filtering occurs because sound waves have positive and negative peaks (crests and troughs). If the arrival delay matches half of a frequency's wavelength, the positive peak of the first signal meets the negative trough of the delayed signal. The result is a complete phase cancellation (acoustic null).

The frequency of the first null is calculated using: f = v / (2 * d), where v is the speed of sound and d is the path distance difference. Subsequent nulls occur at odd multiples of this frequency (3f, 5f, 7f, etc.). Constructive addition occurs at even multiples (2f, 4f, 6f, etc.), boosting those frequencies.

Our interactive comb filtering chart plots this frequency response logarithmically from 20Hz to 20kHz, helping you visualize exactly which registers will be hollowed out.

Frequently Asked Questions

How does temperature affect the speed of sound?

The speed of sound in air is primarily determined by temperature, not pressure or density. As the air gets warmer, molecules move faster, allowing sound waves to propagate more rapidly. For example, at 0°C (32°F), sound travels at about 331.3 m/s, whereas at 20°C (68°F), it travels at approximately 343.4 m/s. This difference directly impacts microphone time alignment in live sound and recording.

What is comb filtering and why does it occur?

Comb filtering is an acoustic phenomenon that happens when two identical or similar signals arrive at different times and are mixed together. Certain frequencies will align perfectly out of phase (canceling each other out, creating nulls), while others will align in phase (doubling in volume, creating peaks). The resulting frequency response graph looks like the teeth of a hair comb, hence the name.

How do mixing engineers fix delay between two microphones?

Engineers correct distance-related delays by applying digital delay to the microphone that is physically closer to the source. This aligns the two signals in the time domain, eliminating phase cancellations, improving punch, and making the mixed sound full and natural.

What is the "3:1 rule" in microphone placement?

The 3:1 rule states that when using multiple microphones, the distance between the microphones should be at least three times the distance from each microphone to its respective sound source. This reduces bleed and keeps the level of the delayed signal low enough that comb filtering is psychoacoustically negligible.

How many milliseconds of delay does one meter of distance create?

At standard room temperature of 20°C (68°F), sound travels at 343.4 meters per second. Therefore, one meter of distance creates a delay of approximately 2.91 milliseconds. In imperial units, one foot of distance creates a delay of about 0.89 milliseconds.

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