SpectraSim
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Duct acoustics · CFD · Heat transfer

Hear your muffler before you build it.

SpectraSim is 3-D duct-acoustics software. It computes transmission loss, insertion loss, radiated noise and resonances, coupled with the flow and temperature your exhaust actually runs at.

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No simulation team? We design it for you
SpectraSim
Screenshot: acoustic pressure field + TL plot [MISSING M12 — product screenshot]
Transmission loss vs. commercial FE code

rms difference 0.12 dB · 20–1000 Hz · curve shape illustrative [MISSING M13 — TL plot from a real run]

In shortWhat is SpectraSim?

SpectraSim is a Windows desktop application for duct acoustics with flow. It predicts the pressure drop and the acoustic performance — transmission loss, insertion loss and radiated sound — of exhaust mufflers and silencers from one 3-D CAD model, coupling a CFD flow solver with a finite-element acoustic solver in one guided workflow.

What you get

Acoustics first, with the flow and heat that change it.

One CAD model and one set of boundaries. The CFD temperature field feeds the acoustic medium, so a hot exhaust shifts the TL curve the way it does on the test bench — by T/Tref\sqrt{T/T_{\mathrm{ref}}} , ×1.73 at 600 °C.

Acoustics

Frequency-domain finite elements in full 3-D: the cross-modes, internals and temperature gradients that 1-D network models miss.

Transmission loss simulation
  • Transmission loss (TL)
  • Insertion loss (IL)
  • Radiated SPL, A-weighted
  • 1/1 and 1/3 octave bands
  • Resonances, domes and notches
  • Acoustic pressure field in 3-D
  • Perforates and absorbing packing
  • Ports with propagating modes

CFD

Steady RANS k-ω SST, incompressible or compressible, with a transient option.

  • Back-pressure
  • Δp₀
  • Loss coefficient ζ
  • Flow split
  • Velocity field
Muffler pressure drop CFD

Heat transfer

Wall heat loss through real wall materials. The temperature field sets the speed of sound in the acoustic model.

  • Wall heat loss
  • Temperature field
  • Hot-gas TL shift
Exhaust heat loss

Validated against measurement, theory and commercial codes.

See the validation
  • 0.12 dB

    TL rms difference against a commercial finite-element code, muffler with an extended-tube chamber, 20–1000 Hz.

    Code-to-code
  • ≈ 2 dB

    Peak TL levels against measured transmission loss of concentric-tube resonators (Sullivan and Crocker, 1978).

    Measured
  • |T| = 1.0000

    Exact one-dimensional straight-duct solution reproduced.

    Analytical
  • 0.017 %

    Energy balance, insulated hot pipe at 700 K, against analytical heat-transfer correlations.

    Analytical

Numbers from the verification runs of 2026-10 (version 0.6.0a1). Acceptance criterion for acoustics against measurement: within ±3 dB over the frequency range of the measurement; flow results are compared case by case as stated.

Applications

Built on duct acoustics. Tuned for exhaust systems.

Any duct that carries sound and flow is in scope. Mufflers and exhaust systems are where SpectraSim is strongest.

Core application

Mufflers and exhaust systems

Automotive, off-highway and mining equipment.

Genset and engine silencers

Reactive and absorptive, multi-chamber, multiple inlets.

Small-engine mufflers

Lawn mowers, small generators and power tools.

HVAC and duct silencers

Splitter and pod silencers, intake and ventilation ducts.
Engineering services

No time or in-house expertise? We design it for you.

Our engineers model, simulate and improve your muffler or duct silencer with SpectraSim. You get the design and a report, with no software to learn.

Request a design study
  1. 01 Send your geometry and targets CAD or drawings, operating conditions, the TL and back-pressure you need.
  2. 02 We simulate and iterate Acoustics, flow and heat in one model, design variants compared.
  3. 03 You receive the design and a report TL, IL, back-pressure and recommended changes, ready for prototyping.
Quick answers

Questions engineers ask first.

What does SpectraSim calculate?
Total-pressure loss Δp₀ and engine back-pressure from CFD, and transmission loss, insertion loss and radiated SPL from finite-element acoustics — in 1/1 and 1/3 octave bands — from the same CAD model.
Does SpectraSim need an internet connection?
No. SpectraSim runs fully offline on a Windows workstation; it has no telemetry and no online activation, so CAD models never leave the computer.
Can you design the silencer for us?
Yes. SpectraSim engineering services model, simulate and improve a muffler or duct silencer from your geometry and targets, and deliver the design with a report. Typical turnaround: [MISSING S01 — typical turnaround] . Engineering services
All questions

Perpetual, yearly or monthly. Every licence includes every feature.

  • Windows workstation
  • Fully offline, no telemetry
  • Your CAD stays on your computer
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