Left and Right Acoustic High-Pass Filter - SM5

Song Meter SM5 User Guide
Core Product
SM5
Accessory

The left and right acoustic channels each have a high-pass filter (HPF) that can be enabled to reduce wind noise and other low-frequency sounds.

When enabled, the high-pass filter reduces the volume of signals below the selected cutoff frequency. If you do not need to record very low-frequency sounds, then enabling the high-pass filter can prevent sounds like wind noise from distorting your recordings.

Options

  • Off (default)
  • 220 Hz
  • 1000 Hz

Example: Using a High-Pass Filter to Remove Wind Noise

Figure 1. Visualization of Wind Blown Directly into Microphone, Without and With High-Pass Filter
Two segments of audio are shown, each visualized as a waveform and a spectrogram. In the upper example, the waveform spans the full available vertical range. At points where the waveform reaches the upper and lower bounds, there are gaps in most of the range of the spectrogram. In the lower example, the waveform takes up a small portion of the available vertical range, and there are no gaps in the spectrogram.

This example shows the same recorded segment from two channels of the same recorder, while air was blown against both microphones. The channel shown at top had its high-pass filter disabled. The channel shown at bottom had its high-pass filter set to 1,000 Hz.

Wind blowing against a microphone creates a strong, low-frequency signal. If that signal is loud enough to clip, or reach the upper and lower bounds of the recorder's range, it creates gaps in the recording where higher-frequency information (such as animal vocalizations) cannot be recorded. The white arrows indicate an instance of this effect.

In the lower example, the high-pass filter has entirely removed the strong low-frequency rumble, and there are no gaps in the recorded audio.