Rating of sound insulation in buildings and of building elements, Part 2: Impact sound insulation

IS 11050 Part 2: Scope and Field of Application

• Scope:
  This part of IS 11050 specifies methods to determine acoustic quantities from measurements in one-third octave bands as per ISO 140/6 and ISO 140/7. It applies to evaluating sound insulation and other acoustic parameters in buildings.

• Field of Application:
  Used primarily for comparing measured acoustic data against reference values to assess compliance or performance.

• Reference Values (Clause 4.2):
  Reference values are provided in Table 3 of the standard, which serves as benchmarks for comparing measurement results.

Key Points:

• Measurements are done in one-third octave bands.
• Reference values from Table 3 are used for comparison.
• Applies to building acoustics, especially sound insulation testing.

Typical Reference Values Table (Example format):

(Exact values to be taken from IS 11050 Part 2 Table 3)

flowchart TD
    A[Measurement in 1/3 Octave Bands] --> B[Apply ISO 140/6 & ISO 140/7]
    B --> C[Obtain Acoustic Quantities]
    C --> D[Compare with Reference Values (Table 3)]
    D --> E[Assessment of Acoustic Performance]

For detailed values and formulas, always refer directly to IS 11050 Part 2 Table 3 and related ISO standards.

IS 11050 Part 2: Normative References & Reference Values

1. Normative References

• IS 11050 Part 2 refers to International Standards and relevant Indian Standards for definitions, test methods, and procedures.
• These referenced standards ensure consistency and comparability of measurements.

2. Clause 4.2: Reference Values (Table 3)

• Table 3 provides reference values used to compare measurement results.
• These values are critical for assessing compliance with vibration or other measurement limits.
• The values are typically presented as:
  • Frequency bands
  • Limit values (e.g., velocity or acceleration in mm/s or m/s²)
  • Measurement conditions

3. Key Specifications

• Reference values are used as benchmarks.
• Measurements outside these values indicate non-compliance or need for mitigation.
• The figure associated with Table 3 illustrates the acceptable range of values across frequency bands.

Typical Format of Reference Values Table (Example):

flowchart LR
    A[Measurement Result] --> B{Compare with Reference Values}
    B -->|Within Limits| C[Compliant]
    B -->|Exceeds Limits| D[Non-compliant - Mitigation Required]

Summary:
Refer to Table 3 in IS 11050 Part 2 for exact reference values. Use these values to assess measurement results against normative standards.

IS 11050 Part 2 — Terms and Definitions: Key Points

• The standard aligns some terminology differently from typical Indian Standards; be cautious when cross-referencing.
• Reference Values (Clause 4.2):
  • Used to compare measurement results in noise/vibration assessments.
  • Specified in Table 3 (not provided here) and illustrated graphically.
• Measurement data is processed in one-third octave bands per ISO 140/6 and ISO 140/7.
• The standard provides rules to calculate quantities (like sound levels, indices) from these banded measurements.

Typical Reference Value Usage (Conceptual):

Calculation Example (from ISO 140 series):

[ L_{total} = 10 \log_{10} \left( \sum_{i} 10^{L_i/10} \right) ]

• (L_i): Level in the ith one-third octave band.

flowchart LR
    A[Measurement in 1/3 Octave Bands] --> B[Apply Reference Values (Table 3)]
    B --> C[Calculate Weighted Levels]
    C --> D[Determine Noise/Vibration Indices]

For exact tables and definitions, refer directly to IS 11050 Part 2 and ISO 140/6 & 140/7.

IS 11050 Part 2: Procedure for Evaluating Single-Number Quantities (Impact Sound Insulation)

This part aligns with ISO 717 and ISO 140 series for impact sound insulation rating.

Key Concepts:

• Single-number quantity (Ln,w): A weighted normalized impact sound pressure level.
• Margin (Mi): The shift applied to the reference curve to fit measured data, expressed as
  [ M_i = 60,dB - L_{n,w} ] where ( L_{n,w} ) is the single-number rating.

Procedure Summary:

1. Measure impact sound levels in one-third octave bands per ISO 140/6 and ISO 140/7.
2. Plot measured spectrum against the reference curve.
3. Shift the reference curve vertically (margin Mi) to minimize deviations within allowed limits.
4. Determine (L_{n,w}) from the shifted curve: [ L_{n,w} = 60,dB - M_i ]

Important Notes:

• The margin (M_i) is positive if the curve shifts favorably (improves rating), negative otherwise.
• This simplification aids building code requirements by reducing complex spectra to a single rating.

Table: Relation between Margin and Single-Number Quantity

flowchart TD
    A[Measure impact sound levels (ISO 140/6, 140/7)] --> B[Plot spectrum in 1/3 octave bands]
    B --> C[Shift reference curve by margin \(M_i\)]
    C --> D[Calculate single-number quantity \(L_{n,w} = 60 - M_i\)]
    D --> E[Use \(L_{n,w}\) for building code requirements]

This concise approach ensures standardized, reproducible impact sound ratings.

IS 11050 Part 2: Statement of Results - Key Points

1. Reference Values (Clause 4.2)

• Use Table 3 for reference values to compare with measurement results.
• Measurements should be in one-third octave bands per ISO 140/6 and ISO 140/7.

2. Determining Quantities from Measurements

• Calculate quantities by integrating or weighting the one-third octave band data.
• Use standard frequency weightings (e.g., A-weighting) as per ISO standards.

3. Single-Number Quantities

• Convert octave band results into single-number indices (e.g., DnT, Rw) using standard methods.
• Typical formula for single-number rating (Rw):

[ Rw = 10 \log_{10} \left( \sum_{i} 10^{L_i/10} \right) ]

where (L_i) = sound levels in each band after corrections.

4. Table 3 (Example format)

(Exact values as per IS 11050 Table 3)

flowchart LR
    A[Measurement in 1/3 Octave Bands] --> B[Apply Corrections]
    B --> C[Compare with Reference Values (Table 3)]
    C --> D[Calculate Single-Number Ratings]
    D --> E[Statement of Results]

Summary: Use Table 3 reference values, measure in 1/3 octave bands (ISO 140/6,7), apply corrections, then calculate single-number ratings for the statement of results.

IS 11050 Part 2 references impact sound insulation evaluation primarily in Parts 6, 7, and 8. For the weighted impact sound improvement index (ΔLw) of floor coverings, the recommended procedure follows:

Key Concepts:

• ΔLw = Difference between impact sound pressure levels of bare floor and floor with covering.
• Measured in a standardized laboratory setup (Part 8) or field conditions (Part 7).
• Impact sound level measured using a standard tapping machine (Part 6).

Procedure Summary:

1. Measure L_n,w (bare floor impact sound level) on a standard floor.
2. Measure L_n,w (floor with covering) under identical conditions.
3. Calculate ΔL_w = L_n,w (bare floor) - L_n,w (with covering).

Typical Formula:

[ \Delta L_w = L_{n,w, \text{bare}} - L_{n,w, \text{covered}} ]

Where:

• (L_{n,w}) = Weighted normalized impact sound pressure level (dB)

Specifications:

• Use standard tapping machine per IS 11050 Part 6.
• Frequency range typically 100 Hz to 3150 Hz.
• Measurements must be frequency-weighted to obtain ΔL_w.

Reference Table (Example):

flowchart LR
    A[Standard Floor] --> B{Measure L_n,w bare floor}
    B --> C[Install Floor Covering]
    C --> D{Measure L_n,w covered floor}
    D --> E[Calculate ΔL_w = L_n,w bare - L_n,w covered]
    E --> F[Evaluate Impact Sound Improvement]

This procedure aligns with IS 11050 Parts 6-8 and international standards for impact sound insulation testing.

Recommended Procedure for Evaluating Equivalent Weighted Normalized Impact Sound Pressure Level (Ln,w,eq) of Bare Concrete Floors (IS 11050 Part 2 / ISO 717-2)

1. Key Definitions

• Ln,w: Weighted normalized impact sound pressure level of the bare floor.
• ALw: Weighted impact sound improvement index of floor covering.
• Ln,w,eq,o: Equivalent weighted normalized impact sound pressure level of bare concrete floor considering reference floor covering.

2. Reference Curve Shifting (Clause 4.3)

• Shift the reference curve (Table 3 values) in 1 dB steps to minimize mean unfavorable deviation ≤ 2 dB.
• Only deviations where measured values exceed reference values are counted.
• Ln,w is the value at 500 Hz of the shifted reference curve.
• Record max unfavorable deviation if > 8 dB.

3. Reference Values for Impact Sound (Table 3 excerpt)

4. Reference Floor (Annex A.3, Table 4)

• Weighted normalized impact sound pressure level of reference floor: Ln,w,r,o = 78 dB

5. Calculation (Annex A.4)

[ \begin{align*} Ln,r &= Ln,r,0 - AL \ AL_w &= Ln,w,r,o - Ln,w,r = 78,dB - Ln,w,r \end{align*} ]

• AL: Reduction of impact sound pressure level measured on bare floor with floor covering.
• Ln,r: Normalized impact sound pressure level of reference floor with covering.
• Ln,w,r: Weighted normalized impact sound pressure level after shifting reference curve (Clause 4.3).

6. Equivalent Weighted Normalized Impact