The Spey-engined aircraft had a lovely professional crackle, specially at rated thrust and OAT below about -5. (Ah, those Canberra mornings). I believe JT8D aircraft (727,737,DC-9) made more real noise and were certainly audible BVR. I think the certification figures said so.
Most youngsters may have missed the joy of the early, fanless, 707s and DC-8s which left even the low bypass second generation engines in a very murky wake.