19. Acoustics

Summary of Noise Standard

      Noise source

      Noise Standard

Users

 Aircraft Noise

(Noise Eposure

Forecast : NEF)

 Helicopter

Noise

Lmax dB(A)

 Road Traffic

Noise L10

(1hour) dB(A)

 Rail Traffic

Noise

 Fixed Noise Source
Kai Tak

Airport

 New Chek

Lap Kok

Airport
All domestic premises including temporary housing accomodation 30 25 85 70 (a) Leq(24hr)              = 65dB(A)

and

(b) Lmax (2300-0700)   = 85 dB(A)

 (a) 5dB(A) below the appropritate Acceptable Noise Levels shown in Table 3 of the Technical Memorandum for the Accessment of Noise from places Other than Domestic Premises, Public Places or Construction Sites and

(b) the prevailing background noise levels.
Hotels and hostels 30 25 85 70
Offices 30 30 90 70
Educational institutions including kindergartens, nurseries and all others where unaided voice communication is required. 30 25 85 65
Places of public worship and courts of law 30 25 85 65
Hospitals, clinics, convalenscances and homes for the aged: -
  • diagnostic rooms
  • wards
 30 25 85 55
Amphitheatres, and auditoria, libraries, performing arts centres and Country Parks depend on use, extent and construction depend on locations and construction

Notes : -

  1. The above standards apply to uses which rely on opened windows for ventilation.
  2. The above standards should be viewed as the maximum permissable noise levels at the external facade.
  3. Definitions of noise units and criteria are included in Appenmdix 4.2.
  4. The NEF contours for the new Chek Lap Kok Airport will be inserted when these are finalized.

Speech Interence Levels (average of contaves centred on 1000, 2000, 4000 Hz) in dB re 2x10-6 Pa.

Distance between talker and listener ( m ) Voices level normal Raised Very loud Shouting

      0.25

    70

 76 82 88

      0.5

    65

 71 77 83

      1.0

    58

 64 70 76

      1.5

    55

 61 67 73

      2.0

    52

 58 64 70

      3.0

    50

 56 62 68

      5.0

    45

 51 57 63

Recommended range of values for relatively steady background sound levels

Listening to music/speech Concert halls, large theatres, opera houses

Multi-purpose halls, small theaters

Courtrooms, Conference rooms, Debating chambers

Small Rooms, e.g. classrooms

 NR:

15-20

20-25

25-30

25-35
Sleep and rest

Study and Consulation

Eating

 Bedrooms, living rooms, lounges, hospital wards

Libraries, executive offices, surgeries

Restaurants, dining rooms

Cafeterias

 25-30

25-35

25-35

below 45
Desk work with telephone use Standard offices 30-40
Repetitive tasks needing limited though General officess

Large kitchens, noisy computer suites

 35-40

below 50
Specific ancillary areas Waiting

Dressing/Changing

Circulation

Toilets

Car Parks

 35-40

below 40

30-40

35-45

below 55
Out of doors In the street, in shopping precincts below 55

( lower if external background levels are low )

*Studio recording and audiometry are normally subject to specific client requirements- NR20 or less.

Notes :

Typical changes in sound insulation with frequency for single partitions

The 'Mass Law' for sound insulation

Coincidence

Noise criteria curves ( N.C. )

Noise rating Curves

Impact insulation class contours

Notes :

  1. Sum of divisions above contour cannot be greater than 32dB
  2. Maximum deficiency at any frequency should not exceed the contour by more than    dB.

Sound transmission class ( STC )

Notes: Deviation allowance within 16% octave bands 125-4000 Hz

  1. A single deviation allowance of 8dB below a contour.
  2. The sum of all deviation below the contour at frequencies not exceed 32dB.

Hz
Materials 63 125 250 500 1k 2k 4k
1. Brickworks, plain or painted 0.05 0.05 0.04 0.02 0.04 0.05 0.05
2. Blockwork ( clinker concrete ) unplastered, unpainted 0.1 0.2 0.3 0.6 0.6 0.5 0.5
3. Concrete, tsoled stone or ganolithic 0.01 0.02 0.02 0.02 0.03 0.04 0.04
4. Plaster, lime or gypsum- on lath or plasterboard are shallows air space(<75mm) 0.1 0.25 0.15 0.1 0.00 0.04 0.05
5. Plywood or hardboard panel mounted over 25mm air space against solid backing with porous absorbent in air space - 0.4 0.25 0.15 0.1 0.1 0.05

NCR : -

Reference :