Response identification in the extremely low frequency region of an electret condenser microphone.

Sensors (Basel, Switzerland) · 2011 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 3235

Study snapshot

PublicationSensors (Basel, Switzerland) · 2011

Study typeengineering

Reported directionUnclear

Evidence ratingInsufficient

Abstract

This study shows that a small electret condenser microphone connected to a notebook or a personal computer (PC) has a prominent response in the extremely low frequency region in a specific environment. It confines most acoustic waves within a tiny air cell as follows. The air cell is constructed by drilling a small hole in a digital versatile disk (DVD) plate. A small speaker and an electret condenser microphone are attached to the two sides of the hole. Thus, the acoustic energy emitted by the speaker and reaching the microphone is strong enough to actuate the diaphragm of the latter. The experiments showed that, once small air leakages are allowed on the margin of the speaker, the microphone captured the signal in the range of 0.5 to 20 Hz. Moreover, by removing the plastic cover of the microphone and attaching the microphone head to the vibration surface, the low frequency signal can be effectively captured too. Two examples are included to show the convenience of applying the microphone to pick up the low frequency vibration information of practical systems.

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AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeengineering

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureELF

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

In a specific experimental setup using a small air cell (hole drilled in a DVD plate) with a speaker and electret condenser microphone on opposite sides, the microphone captured signals in the 0.5–20 Hz range when small air leakages were allowed at the speaker margin. Removing the microphone’s plastic cover and attaching the microphone head to a vibration surface also enabled effective capture of low-frequency signals.

Outcomes measured

Microphone response/signal capture in extremely low frequency range (0.5–20 Hz)
Low-frequency vibration information capture in practical systems

Limitations

Specific environment/setup noted; generalizability not established in abstract
No sample size or quantitative performance metrics reported in abstract
Not a biological/health study; relevance to EMF exposure/health outcomes not addressed

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": "ELF",
    "source": "other",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Microphone response/signal capture in extremely low frequency range (0.5–20 Hz)",
    "Low-frequency vibration information capture in practical systems"
  ],
  "main_findings": "In a specific experimental setup using a small air cell (hole drilled in a DVD plate) with a speaker and electret condenser microphone on opposite sides, the microphone captured signals in the 0.5–20 Hz range when small air leakages were allowed at the speaker margin. Removing the microphone’s plastic cover and attaching the microphone head to a vibration surface also enabled effective capture of low-frequency signals.",
  "effect_direction": "unclear",
  "limitations": [
    "Specific environment/setup noted; generalizability not established in abstract",
    "No sample size or quantitative performance metrics reported in abstract",
    "Not a biological/health study; relevance to EMF exposure/health outcomes not addressed"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "electret condenser microphone",
    "extremely low frequency",
    "0.5–20 Hz",
    "vibration measurement",
    "air cell",
    "speaker",
    "signal capture"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.3390/s110100623
PubMed: 22346594

Read the original paper →

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