Overview
IEC TR 61305-6:2005 provides recommended procedures for subjective listening tests on loudspeakers intended for home use. It complements objective measurements (e.g., IEC 60268-5) by defining how to conduct and evaluate listening tests so that sound characteristics of different loudspeakers can be compared reproducibly. The report focuses on two validated test formats: single stimulus ratings and paired comparisons and is applicable to stereo and multichannel systems.
Key topics and technical requirements
- Scope and purpose
- Applies to loudspeakers conforming to IEC 61305-5 and intended for domestic listening.
- Designed to establish standard comparison methods for perceived sound quality.
- Listening room and acoustics
- Typical room volume: 80 m³ ± 20 m³, room height 2.75 m ± 0.25 m; rectangular plan (side ratio ≤ 2:1).
- Reverberation time requirements with stability across octaves (measurement per ISO 3382); RT must not vary more than +25 % / −20 % within 400 Hz–8 kHz.
- Background noise (A-weighted) limited to ≤ 25 dB AFm.
- Loudspeaker placement and masking
- Loudspeakers hidden behind an acoustically transparent screen to prevent visual bias.
- Typical placement: manufacturer-recommended positions, at least 0.5 m from walls; stereo angle such that each listener’s angle is ≥ 45°.
- Electrical and level requirements
- Use a source, level control and a power amplifier with low output impedance and sufficient power (no clipping).
- Tone controls set flat; system deviations limited to ±0.5 dB from 20 Hz to 20 kHz (measured at system input and amplifier output).
- Level setting: pink noise with A-weighted level ≈ 75 dB as practical reference.
- Test procedures and analysis
- Detailed protocols for single stimulus ratings (absolute scoring) and paired comparisons (relative ranking).
- Guidance on programme material, listener selection and number, test duration, questionnaires, statistical evaluation (variance analysis, factor analysis, reliability).
Applications and users
- Who uses it:
- Loudspeaker manufacturers (R&D, QA), independent test laboratories, audio reviewers, certification bodies.
- Practical applications:
- Product development and tuning based on perceptual feedback.
- Comparative bench-marking of consumer loudspeakers.
- Formal listening test design for reviews and conformance reporting.
- Multichannel/surround listening evaluations (procedures scale to multiple channels).
Related standards
- IEC 61305-5 - Minimum performance requirements for loudspeakers (referenced).
- IEC 60268-5 - Objective loudspeaker measurement methods.
- ISO 3382 - Reverberation time and room acoustics.
- IEC TR 61305-6 complements these documents by standardizing subjective listening protocols for home loudspeaker assessment.