High-Frequency Noise Monitor 5.0

The "High-Frequency Noise Monitor" is a specialized tool designed for the analysis of noise in high-frequency bands exceeding 8 kHz. It addresses the concern of exposure to artificial high-frequency noise that, while inaudible to the human ear, may be present in daily environments.

This application serves as an effective monitoring solution for such high-frequency sounds, allowing users to examine their occurrence and impact. High-frequency noise can arise from various sources, and it is essential for users to understand its implications.

For instance, harmonic noise often emanates from the internal components of electronic devices or power lines connected to power conversion units, such as AC-DC adapters. Depending on the intensity of this noise, it may potentially interfere with surrounding equipment.

Moreover, some devices intentionally generate high-frequency sounds to deter pests such as rats and weasels, and these noises can vary based on the specific vermin targeted. Some models include sensors that adjust volume and frequency over time, which might inadvertently contribute to noise issues that could adversely affect human health when placed nearby.

High-frequency sounds rarely maintain a constant volume or frequency; instead, they typically exhibit cyclical or random patterns, making detection challenging. This application leverages the built-in microphone of the iPhone to capture these fluctuations in real-time, facilitating continuous frequency analysis.

The app retains PCM data for a duration of 20 seconds prior to the conclusion of measurement and subsequently generates a visual spectrogram that represents FFT and octave band analysis results. This spectrogram presents frequency spectrum analysis over time, displaying signal strength through a color gradient. Users can thus visually assess the presence of high-frequency noise.

Features:

• Main: Real-time frequency analysis function.
  • Continuous measurement with automatic cessation after approximately 180 seconds.
  • Display of maximum frequency and power level in dB (20 μPa standard).
  • Approx. 10-second time trace display.
  • Three levels of adjustable gain: 0dB - 90dB / -10dB - 80dB / -20dB - 70dB.
• Analysis: FFT/octave band spectrogram analysis function.
  • FFT spectrogram analysis available.
  • Octave spectrogram analysis implemented.
  • Three levels of display gain switching.
  • Playback function for approximately 20 seconds of captured sound.
  • Playback sound filter utilizing an 8 kHz high-pass filter to eliminate low-mid range noise.
• Snapshot (Snap): Option to save analysis results as image files.

Operation Procedure:

1. Sound measurement and real-time frequency analysis (Main): Initiate measurement by tapping the Start button in Main mode. Real-time frequency analysis results will be displayed alongside a trace of frequency variations over time. Numerical values representing maximum detected frequency and signal level are also available.
2. Spectrogram analysis (Analysis): Following measurement in Main mode, tap the Analysis button to engage spectrogram analytical options. Select either FFT or OCT to view corresponding spectrogram displays.

Notes:

• The accuracy of high-frequency sound measurements is contingent upon the sensitivity characteristics of the iPhone's built-in microphone; variations may occur across different iPhone models.
• This application does not support wireless (Bluetooth) headphones or headsets.
• Upon first accessing the Microphone and Photos post-installation, iOS will prompt for authorization for access. If these settings are not enabled, privacy restrictions will prevent access. Users should ensure permissions are appropriately set via "Settings > Privacy & Security > Photos or Microphone".

For further information regarding this application, please consult the iOS app support page.