Trinnlyd

Trinnlyd is the acoustic term for noise generated by mechanical impacts, such as footsteps, that travels through a building’s structure and is heard in adjacent spaces. It is a common concern in multi-unit buildings where activity in one dwelling is audible in neighboring units. The primary transmission path is through floors and ceilings, but sound can also reach other rooms via flanking routes such as walls, ducts, or structural elements.

Assessment of trinnlyd is done with standardized measurements that simulate footfalls, typically using a tapping or impact source. Results are reported as a weighted impact sound level, often denoted as a single-number index (for example L'nT,w), expressed in decibels. Lower values indicate better impact sound insulation. Target values vary by country and building type, and modern standards generally require lower levels in new constructions, while older buildings may exhibit higher trinnlyd.

Design and construction practices influence trinnlyd. Key strategies to reduce impact noise include decoupled floor–ceiling assemblies, the use of damping or resilient layers, and adding mass to the floor structure. Finishes such as carpets with underlay can further reduce perceived impact noise, while rigid, poorly damped assemblies tend to transmit more sound. Attention to flanking paths and proper detailing during construction are also important for achieving satisfactory performance. Ongoing maintenance and renovations can alter trinnlyd performance, so accurate retrofits and testing are often employed to meet regulatory or client specifications.