A Node Red flow for PC which reads from COM3 and plays the audio file (as coded) in the browser

PC-OPS241 NodeRed.json

[
    {
        "id": "90b76976.49ff38",
        "type": "tab",
        "label": "Flow 1"
    },
    {
        "id": "52bcfbfe.e89d74",
        "type": "switch",
        "z": "90b76976.49ff38",
        "name": "test for slow/fast",
        "property": "n",
        "propertyType": "msg",
        "rules": [
            {
                "t": "btwn",
                "v": "-1.1",
                "vt": "num",
                "v2": "1.1",
                "v2t": "num"
            },
            {
                "t": "else"
            }
        ],
        "checkall": "true",
        "outputs": 2,
        "x": 263,
        "y": 208,
        "wires": [
            [],
            [
                "a8f2c7e7.eb00e8",
                "272f1ce8.3c55d4"
            ]
        ]
    },
    {
        "id": "34d52df0.10c8e2",
        "type": "function",
        "z": "90b76976.49ff38",
        "name": "parseFloat into msg.n",
        "func": "\nvar rtn = {n:0.0};\nrtn.n = parseFloat(msg.payload);\n\nreturn rtn;\n",
        "outputs": 1,
        "noerr": 0,
        "x": 256,
        "y": 128,
        "wires": [
            [
                "52bcfbfe.e89d74"
            ]
        ]
    },
    {
        "id": "ce956e12.d5c97",
        "type": "serial in",
        "z": "90b76976.49ff38",
        "name": "COM3",
        "serial": "66517bad.78aab4",
        "x": 189,
        "y": 41,
        "wires": [
            [
                "34d52df0.10c8e2"
            ]
        ]
    },
    {
        "id": "272f1ce8.3c55d4",
        "type": "debug",
        "z": "90b76976.49ff38",
        "name": "",
        "active": false,
        "console": "false",
        "complete": "n",
        "x": 499,
        "y": 188,
        "wires": []
    },
    {
        "id": "a8f2c7e7.eb00e8",
        "type": "change",
        "z": "90b76976.49ff38",
        "name": "",
        "rules": [
            {
                "t": "set",
                "p": "payload",
                "pt": "msg",
                "to": "\\users\\jim\\OneDrive\\documents\\sound_recordings\\SlowDown1s.wav",
                "tot": "str"
            }
        ],
        "action": "",
        "property": "",
        "from": "",
        "to": "",
        "reg": false,
        "x": 296,
        "y": 303,
        "wires": [
            [
                "8e46c031.20885"
            ]
        ]
    },
    {
        "id": "8e46c031.20885",
        "type": "file in",
        "z": "90b76976.49ff38",
        "name": "",
        "filename": "\\users\\jim\\OneDrive\\Documents\\sound_recordings\\SLowDown1s.wav",
        "format": "",
        "x": 476,
        "y": 374,
        "wires": [
            [
                "74cf2d23.3c2d84"
            ]
        ]
    },
    {
        "id": "74cf2d23.3c2d84",
        "type": "play audio",
        "z": "90b76976.49ff38",
        "name": "",
        "voice": "",
        "x": 341,
        "y": 454,
        "wires": []
    },
    {
        "id": "66517bad.78aab4",
        "type": "serial-port",
        "z": "",
        "serialport": "COM3",
        "serialbaud": "9600",
        "databits": "8",
        "parity": "none",
        "stopbits": "1",
        "newline": "\\n",
        "bin": "false",
        "out": "char",
        "addchar": false
    }
]