So this, then?

use strict;
use warnings;

use Test::More tests => 4;

my $voices = {
    'Microsoft Hedda Desktop - German'                  => 3,
    'Microsoft Haruka Desktop - Japanese'               => 4,
    'Microsoft Zira Desktop - English (United States)'  => 0,
    'Microsoft Hazel Desktop - English (Great Britain)' => 1,
    'Microsoft David Desktop - English (United States)' => 2,
    'Microsoft Huihui Desktop - Chinese (Simplified)'   => 5
};

my $engtest = bestvoice ('English', $voices);
cmp_ok $voices->{$engtest}, '>', 0, 'English has positive value';
like $engtest, qr/English/, 'English matched in key';
is bestvoice ('German', $voices), 'Microsoft Hedda Desktop - German',
  'German matched in key';
is bestvoice ('Esperanto', $voices), undef, 'Esperanto not matched';

sub bestvoice {
    my ($want, $v) = @_;
    my @poss = grep {/$want/} keys %$v;
    if ($#poss > 0) {
        @poss = grep { $v->{$_} } @poss;
    }
    return $poss[0];
}
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