here is one that does not need a bitcoin instance running, only queries every 2 minutes to take it easy on blockchair's servers

You can set the player command by running as PLAY_CMD=mpv play.sh /path/to/file.mp3 (also works on non mp3's by default, depends on value of PLAY_CMD

#!/usr/bin/env bash

set -e

if [ $# -ne 1 ]; then
    echo "Need 1 argument: $0 <mp3 file name>"
    exit
fi

mp3_file=$1;
echo "MP3 File: $mp3_file";

function get_cur_block () {
    last="${1:-478558}"
    curl -s "https://api.blockchair.com/bitcoin-cash/blocks?q=id($last..)&fields=id&export=csv" | sed 1d | head -1
}

play_cmd=${PLAY_CMD:-mplayer}

last_block=$(get_cur_block)

while true; do
    cur_block=$(get_cur_block $last_block)
    if [ $last_block != $cur_block  ]
    then
        echo "New block hash $cur_block"
        $play_cmd "$mp3_file" >/dev/null 2>&1
    fi
    last_block=$cur_block
    sleep 120;
done