Some of our old films have rather poor quality optical sound tracks. Many viewers find the original dynamic range of cinema films excessive so this is often reduced prior to transmission. This has the effect of further increasing the background noise in quiet passages. To counter this various types of audio processing are sometimes applied to reduce the background noise. Unfortunately this often has to be a compromise between noise and intelligibility. Other suggestions are to investigate the sound adjustments available on the TV and if available to try the effect boosting the high frequencies (treble) and cutting the low frequencies (bass) to improve intelligibility.