Trane TRG-TRC007-EN manual Room effect See receiver room correction

Page 80

Glossary

reverberant field A uniform, or diffuse, sound field that is the opposite of a free field. In a perfectly reverberant field, the sound-pressure level is equal at all points.

reverberant room A specially constructed room with reflective walls, floors, and ceilings. When a sound source is placed in this room, the sound waves bounce back and forth between the reflective walls many times. In a perfectly reverberant room, the sound-pressure level is equal at all points in the room.

reverberant-room method A common method for testing HVAC equipment. It uses a specially-constructed room to create a uniform, or diffuse, sound field by reflecting and mixing the sound waves. The walls, floor, and ceiling of the reverberant room are hard in order to cause multiple reflections of sound waves. In this environment, the sound pressure is essentially the same at all locations in the room. Sound-pressure levels are measured in the reverberant room and used to calculate sound-power levels for the piece of equipment.

room criteria (RC) A single number used to describe sound in a room. It uses a series of curves and reference lines for plotting sound pressure by octave band and determining the RC value and a descriptor of the sound quality (i.e., hiss, rumble).

room effect See receiver room correction.

semireverberant field A sound field that is somewhere between a free field and a reverberant field. The walls and ceiling of a room prevent the sound from behaving in a free field manner, however, these surfaces are not perfectly reflective. Some of the sound is reflected by these surfaces, but a portion is absorbed.

sone A unit of measure, using a linear scale, used to describe the loudness of a sound. A sone is the linear equivalent to a phon.

sound Audible emissions resulting from the vibration of molecules within an elastic medium. It is generated by either a vibrating surface or the movement of a fluid. In the context of building HVAC systems, this elastic medium can be either air or the building structure. For structurally-borne sound to become audible, however, it must first become airborne.

sound power The acoustical energy emitted by the sound source. It is not affected by the environment.

sound pressure An audible pressure disturbance in the atmosphere that can be measured directly. Its magnitude is influenced not only by the strength of the source, but also by the surroundings and the distance from the source to the listener. Sound pressure is what our ears hear and what sound meters measure.

source–path–receiver model A systematic approach to analyzing the sound in a space. It traces sound from the source to the location where we want to predict the sound (the receiver). How the sound travels between the source and

TRG-TRC007-EN

73

Page 79 Page 81
Image 80
Page 79 Page 81
Contents Air Conditioning Clinic Fundamentals of Hvac Acoustics Business Reply Mail Comment Card One of the Fundamental SeriesFundamentals of Hvac Acoustics Preface Fundamentals of Hvac AcousticsContents TRG-TRC007-EN Fundamentals of Sound Fundamentals of SoundWhat is Sound? What is Sound?Sound Wave and Frequency Wavelength Broadband Sound Broadband Sound and TonesOctave Bands Octave BandsLogarithmic sums One-Third Octave Bands Sound Power and Sound Pressure Sound Power and Sound PressureAn Analogy DB = 10 log DecibelLogarithmic Scale 10 ´ logEquation for Sound Power Equation for Sound PressureLogarithmic Addition of Decibels 50 dB + 44 dB = 51 dBHuman Ear Response Sound Perception Rating MethodsHuman Ear Loudness Contours Single-Number Rating Methods Response to TonesSingle-Number Rating Methods C Weighting Sound Perception and Rating MethodsWeighting Example Weighting Noise Criteria NC Curves NC-39 Room Criteria RC Curves MPa DB ref Pressure Sound Perception and Rating Methods RC-31 R Phon and Sone Octave-Band Rating Method Octave-Band Rating MethodAcoustical Analysis Acoustical AnalysisSetting a Design Goal Setting a Design GoalAcoustical Analysis Acoustical Analysis Source-Path-Receiver AnalysisSource-Path-Receiver Model Typical Sound Paths AirborneExamples of a Single Sound Path Example of Multiple Sound PathsIdentifying Sound Sources and Paths Modeling Sound Paths Sound-Path ModelingSupply Algorithms for Sound-Path Modeling Computerized Analysis Tools Attenuation and Regeneration Terms Used in Sound-Path ModelingSound Transmission Insertion loss IL Noise reduction NR Transmission loss TL Absorption Reflected Sound Receiver Sound Correction Equipment Sound Rating Equipment Sound RatingFree Field Fields of Measurement= L p1 20 log Distance Correction in a Free FieldLot Near Field Reverberant Field Semireverberant Field Rating Hvac Equipment Hvac Equipment Sound RatingReverberant-Room Method Free-Field Method Industry Standards Ducted Air-Handling Equipment Air Handler Test Configurations Former Methods of Sound Testing ARI Standard Sound Power by Octave Band Review Review-Period OneReview-Period Two Noise criteria NC Room criteria RCReview-Period Three Review-Period Four Review Quiz Questions for PeriodOctave-band frequency, Hz Answers Glossary Glossary Room effect See receiver room correction Glossary Trane
Top Page Image Contents