#!/usr/bin/perl

use strict;
use warnings;

while ( my $line = <DATA> ) {
    my @candidates = $line =~ m{ "([^"]+)" }xmsg;
    my @paths      = grep{ m{/} }@candidates;

    print sprintf "found on line %s: %s\n", $., join ', ', @paths;
}

__DATA__
soundSet = { name = "bus_modern", horn = "vehicle/truck_modern/horn.wav" }
id = "vehicle/bus/citaro/lod_0_w2.msh",
"vehicle/bus/berkhof_duvedec/berkhof_duvedec_lod_0_w2.msh", "vehicle/bus/berkhof_duvedec/berkhof_duvedec_lod_0_w3.msh", 

$ perl paths.pl 
found on line 1: vehicle/truck_modern/horn.wav
found on line 2: vehicle/bus/citaro/lod_0_w2.msh
found on line 3: vehicle/bus/berkhof_duvedec/berkhof_duvedec_lod_0_w2.msh, vehicle/bus/berkhof_duvedec/berkhof_duvedec_lod_0_w3.msh