Closed headphones gain isolation but become sensitive to leakage effects.

Evidence

The construction of large headphones depends on what compromise is made between sound isolation and the effect of leakage. To isolate the ear from external noise, the headphone may be closed. In this case, the transfer function of the headphone is sensitive to leakage. Alternatively, in open headphone design, the headphone is not sealed, and the sound from the headphone leaks out in a controlled manner. This makes the transfer function insensitive to leakage from the joint between the headphone cushion and the head. However, with open headphone design there is no isolation from external noise. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 480

To isolate the ear from external noise, the headphone may be closed. In this case, the transfer function of the headphone is sensitive to leakage. Alternatively, in open headphone design, the headphone is not sealed, and the sound from the headphone leaks out in a controlled manner. This makes the transfer function insensitive to leakage from the joint between the headphone cushion and the head. However, with open headphone design there is no isolation from external noise. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 480

Categorization

• XREF: The isolation-vs-leakage tradeoff is a design principle that maps onto many communication-audio system choices. — connects to: In homes, air leaks dominate sound isolation more than the glazing itself — David Howard, Jamie Angus, coustics and Psychoacoustics, 2173
• corroborated: 3 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 480