Why can adding turbochargers make a sports-car exhaust note feel less raw?

Answer: The turbine extracts exhaust energy before it reaches the tailpipe

The compressor smooths intake air so exhaust pulses become quieter — Not quite. It is tempting to blame the compressor because it conditions the air going into the engine, and smoother intake air can affect combustion. But the compressor is on the intake side and is driven by the turbine in the exhaust stream. The acoustic change begins with exhaust energy being tapped in the exhaust path, not with intake smoothing.

The turbine housing blocks exhaust sound waves like a muffler — Not quite. A turbocharger does put a turbine housing in the exhaust path, so it is easy to picture it acting like a muffler. But the housing is not the main acoustic cause: the turbine extracts energy from the exhaust flow to drive the compressor. Once that energy is removed, less raw exhaust energy is left to become tailpipe sound.

The turbine extracts exhaust energy before it reaches the tailpipe ✓ — Right. The turbocharger's turbine sits in the exhaust stream and extracts energy to drive the compressor. That makes more power and efficiency possible, but it also means less raw exhaust energy travels straight to the outlet. Some road tests describe modern turbo performance cars as muted or muffled compared with earlier or more naturally exposed engines.