A laboratory study for assessing speech privacy in a simulated open-plan office

Area of Science:

• Acoustics
• Psychoacoustics
• Architectural Engineering

Background:

• Speech privacy is crucial in open-plan offices.
• Traditional metrics may not fully capture speech privacy.
• New single-number quantities offer potential for improved assessment.

Purpose of the Study:

• To evaluate the effectiveness of two new single-number quantities, DL(2,S) and L(p,A,S,4)m, in assessing speech privacy.
• To determine the influence of these quantities on speech intelligibility and listening difficulty in open-plan office environments.
• To provide data for designing better open-plan offices and acoustic guidelines.

Main Methods:

• Modeled open-plan offices with varying DL(2,S) and L(p,A,S,4)m values.
• Conducted auditory experiments with 20 subjects rating Korean sentences.
• Measured speech intelligibility and listening difficulty at source-receiver distances of 8, 16, and 24 meters with a fixed background noise level of 30 dBA.

Main Results:

• Speech intelligibility was unaffected by DL(2,S) or L(p,A,S,4)m at 8m.
• Listening difficulty was significantly impacted by DL(2,S) and L(p,A,S,4)m at all tested distances.
• Both intelligibility and listening difficulty were sensitive to distraction distance (r(D)).
• Listening difficulty showed higher sensitivity to variations in DL(2,S) and L(p,A,S,4)m in high speech transmission performance sound fields.

Conclusions:

• The single-number quantities DL(2,S) and L(p,A,S,4)m, based on spatial sound pressure level distribution, are associated with speech privacy in open-plan offices.
• These metrics are suitable for assessing speech privacy, particularly at larger distances.
• Findings support the use of these quantities in the design and acoustic guidelines for open-plan offices.