You're right: for acoustical standing waves, a displacement antinode appears where there's a pressure node.
I think of it like this: find where the pressure nodes are. At these locations, the spatial pressure _gradient_ is largest in magnitude, meaning that at those locations, the resulting velocities are highest.
At pressure antinodes, one has constituent particles bunching up or dispersing, but equal amounts in either direction, so that right at the pressure antinode, there's a velocity node.
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From: Jeff Loats <jeff.loats@gmail.com>
To: Forum for Physics Educators <Phys-L@phys-l.org>
Sent: Tuesday, March 25, 2014 10:46 AM
Subject: [Phys-L] Acoustics: Does a speaker create a displacement antinode?
Hello,
I'm having a "I thought I knew this, but I'm confusing myself" kind of
moment. I appreciate your help:
Imagine two speakers pointed at each other from some distance apart. At
certain separations we should get a standing wave along the line connecting
them. If we set it up to get such a standing wave and if we measure
displacement of the air, will there be displacement antinodes at each
speaker? Meaning a pressure node at each speaker?